Systems and methods of protecting wireless power receivers using multiple rectifiers and establishing in-band communications using multiple rectifiers

ABSTRACT

An exemplary embodiment of a wireless power receiver comprises a wireless-power-receiving antenna configured to receive radio frequency (RF) signals, and convert energy from the received RF signals into an alternating current. The power receiver also comprises a primary rectifier configured to: (i) receive a first portion of the alternating current, and (ii) rectify the first portion of the alternating current into primary direct current having a first power level, the primary direct current used to provide power or charge to an electronic device; and a secondary rectifier configured to: (i) receive a second portion of the alternating current, and (ii) rectify the second portion of the alternating current into a secondary direct current having a second power level. The second power level of the secondary direct current is less than the first power level of the primary direct current.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 62/907,234, filed Sep. 27, 2019, and to U.S. Provisional ApplicationSer. No. 62/903,675, filed Sep. 20, 2019. Each of these applications ishereby incorporated by reference.

TECHNICAL FIELD

The embodiments herein generally relate to antennas, software, anddevices used in wireless power transmission systems and, morespecifically, to systems and methods of receivers with rectifierscapable of being used for communicating, warning of power fluctuations,and protecting against power surges.

BACKGROUND

Conventional wireless power transmission systems, such as charging pads,utilize both RF signals and induction to generate a magnetic field thatis used to charge a device. These charging pads (i.e., transmitters)have to communicate with receivers to ensure that the device to becharge is not damaged by an unexpected surge in power or a power loss.To overcome such issues, the current approach has been to add a wirelesscommunication chip (e.g., a Bluetooth radio) to both the transmitter andthe receiver, which allows the devices to communicate with each other.However, the addition on these communication chips can be costly, whichincreases the cost of the wireless power transmission systems. Inaddition, in electronic devices where space is at a premium, thewireless communication chips occupy valuable shape.

Furthermore, establishing a communication connection between thetransmitter and the receiver takes time, which can slow the time tostart sending power from the transmitter to a receiver. Such a result isundesirable, because the wireless transmission of power is intended tobe less involved than plugging in a device into a power source.

SUMMARY

Accordingly, there is a need for wireless charging systems (e.g., radiofrequency (RF) charging pads) that address the problems identifiedabove. To this end, systems and methods are described herein that arecapable of allowing receivers to communicate and prepare for changes inpower without having a dedicated communication chip (e.g., a Bluetoothradio). In some embodiments, such system and methods use to tworectifiers to solve the identified problems. It is also understood thatin a two rectifier embodiment, a first rectifier is used to convert RFpower to useable direct current (DC) to charge an electronic devicewhile a second rectifier is configured to receive a smaller portion ofpower than the first rectifier, whereby this smaller portion of power isnot used to charge the electronic device.

Typically, outputs of rectifiers are coupled to capacitors capable ofreducing ripple. These capacitors are sized to match the outputteddirect current, and the larger the direct current, the larger thecapacitor needs to be to reduce ripple. However, these capacitors delaythe detection (by either not charging or discharging fast enough) inincoming power. As a result, a second smaller rectifier that receives asmaller portion of power is capable of detecting changes in power fasterthan the components coupled to the first (i.e., larger power handling)rectifier. And once the second (i.e. smaller power handling) rectifierdetects the change in power, it can communicate with the componentscoupled to the output of the first rectifier, and warn them that a powerchange has occurred.

In another aspect, this two rectifier embodiment allows for the secondrectifier to adjust the impedance of the receiver causing a portion ofthe received RF power to be reflected back to the wireless powertransmitter. By adjusting this impedance, the wireless power receivercan communicate with the wireless power transmitter. In one example, thewireless power transmitter can modulate its impedance (e.g., throughcontrol of the second rectifier) to signal the wireless powertransmitter that a reduction in power is required by the wireless powerreceiver, or simply that power is no longer required.

(A1) In some embodiments, the solution explained above can beimplemented on a wireless power receiver that includes awireless-power-receiving antenna configured to receive radio frequency(RF) power signals, and convert energy from the received RF signals intoan alternating current. The wireless power receiver also includes aprimary rectifier that is configured to: (i) receive a first portion ofthe alternating current, and (ii) rectify the first portion of thealternating current into primary direct current having a first powerlevel, the primary direct current used to provide power or charge to anelectronic device. The wireless power receiver also includes a secondaryrectifier that is configured to: (i) receive a second portion of thealternating current, and (ii) rectify the second portion of thealternating current into a secondary direct current having a secondpower level. The second power level of the secondary direct current isless than the first power level of the primary direct current. While afirst voltage associated with the primary direct current and a secondvoltage associated with the secondary direct current can be similar, thepower levels (the first and second power levels above) differ becauseload resistances for the primary and secondary direct currents aredifferent.

(A2) In some embodiments of A1, the second power level of the secondarydirect current indicates whether the antenna is receiving RF signalsfrom a wireless-power-transmitting device.

(A3) In some embodiments of A2, an RF coupler is coupled to the antenna,and the RF coupler includes distinct first and second outputs.Furthermore, the primary rectifier is coupled to the first output of theRF coupler and the secondary rectifier is coupled to the second outputof the RF coupler.

(A4) In some embodiments of A3, at least one impedance matching networkis positioned between and coupled to the first output of the RF couplerand the secondary rectifier, whereby the at least one matching networkis configured to match an impedance of a source of the RF signals.

(A5) In some embodiments of A3, at least one impedance matching networkis positioned between and coupled to an input of the RF coupler and theantenna, whereby the at least one matching network is configured tomatch an impedance of a source of the RF signals.

(A6) In some embodiments of A3, the wireless power receiver alsoincludes (i) one or more additional electrical components that are usedto deliver the primary direct current that is used to power or charge tothe electronic device and (ii) a controller configured to: (a) detectthat the second power level of the secondary direct current satisfiesone or more power-detection thresholds that indicate that the antenna isreceiving RF signals from a wireless-power-transmitting device and (b)in response to detecting that the second direct current satisfies theone or more power-detection thresholds, send a signal that causes eachof the one or more additional electrical components to prepare forreceiving the primary direct current.

(A7) In some embodiments of A6, the one or more power-detectionthresholds are satisfied when a voltage of the secondary direct currentis in a range of approximately 5 volts to 30 volts. In somecircumstances, the range can be either broadened (e.g., to be 1 volts to40 volts), or narrowed (e.g., to be 5 volts to 10 volts).

(A8) In some embodiments of A7, detecting that the second power level ofthe secondary direct current satisfies one or more power-detectionthresholds is performed by comparing the second power level to arespective power-detection threshold of the one or more power-detectionthresholds at a first measurement point, a second measurement point, orboth the first and second measurement points.

(A9) In some embodiments of A8, the first measurement point is locatedbefore a voltage divider that is configured to step down the voltage ofthe secondary direct current, and the second measurement point islocated after the voltage divider.

(A10) In some embodiments of A6, the second portion of the alternatingcurrent is approximately less than 1% of the alternating current. Insome embodiments, having the alternating current less than 1% minimizesimpact on overall RF to DC conversion efficiency.

(A11) In some embodiments of A6, the wireless power receiver alsoincludes: (i) a first storage component and (ii) a second storagecomponent having a lower storage capacity that is less than the firststorage component. Furthermore, the first storage component is coupledto an output of the primary rectifier while the second storage componentis coupled to an output of the secondary rectifier. Moreover, the secondstorage component, due to its lower storage capacity, is configured todischarge faster than the first storage component, whereby discharge ofthe second storage component indicates to the wireless power receiverthat RF signals are no longer being received at the antenna.

(A12) In some embodiments of any of A1-A11, the secondary rectifier iscomposed of: (i) an input configured to receive the second portion ofthe alternating current, (ii) a first diode, and (iii) a second diode.The input of the secondary rectifier is coupled to: a cathode of a firstdiode, wherein an anode of the first diode is coupled to a ground; andan anode of a second diode, wherein a cathode of the second diode iscoupled to an output of the secondary rectifier.

(A13) In some embodiments of any of A1-A12, the secondary rectifier iscomposed of: (i) an input configured to receive the second portion ofthe alternating current, (ii) a first diode-connected transistor, and(iii) a second diode-connected transistor. The input of the secondaryrectifier is coupled to: (i) a first diode-connected transistor, whereinthe first diode-connected transistor is connected to a ground; and (ii)a second diode-connected transistor, wherein the second diode-connectedtransistor is connected to an output of the secondary rectifier.

(A14) In some embodiments of any of A3-A13, the RF coupler is adirectional coupler.

(A15) In some embodiments of any of A3-A13, the RF coupler is acapacitive coupler.

(A16) In some embodiments of any of A3-A13, the RF coupler is aresistive coupler.

(B1) In another aspect, a method of communication between a wirelesspower receiver to a wireless power transmitter is performed. In someembodiments, the method includes receiving, by an antenna of thewireless power receiver, radio frequency (RF) signals from the wirelesspower transmitter, whereby the wireless power receiver substantiallymatches an impedance of the wireless power transmitter. The method alsoincludes, while receiving the RF signals from the wireless powertransmitter: (i) determining whether a communication criterion issatisfied, and (ii) in accordance with a determination that thecommunication criterion is satisfied, introducing an impedance mismatchbetween the wireless power receiver and the wireless power transmitterthat causes a portion of the RF signals to be reflected by the antennaas a modulated signal. The transmitter is configured to receive andinterpret the modulated signal without using a separate communicationradio.

(B2) In some embodiments of Bl, introducing the impedance mismatchincludes creating one or more impedance mismatches between the wirelesspower receiver and the wireless power transmitter interspersed with oneor more impedance matches between the wireless power receiver and thewireless power transmitter forming the modulated signal.

(B3) In some embodiments of B2, the wireless power transmitterinterprets the modulated signal as an instruction to cease sending theRF signals to the wireless power receiver.

(B4) In some embodiments of B2, the wireless power transmitterinterprets the modulated signal as an instruction to adjust transmissioncharacteristics of the RF signals to the wireless power receiver.

(B5) In some embodiments of any of B1-B4, the method further includes,after introducing the impedance mismatch and while continuing to receivethe RF signals from the wireless power transmitter, matching theimpedance between the wireless power receiver and the wireless powertransmitter, which stops reflection of the portion of the RF signals bythe antenna.

(B6) In some embodiments of any of B1-B5, the wireless power transmitterceases to transmit the RF signals to the wireless power receiver inresponse to receiving the modulated signal.

(B7) In some embodiments of any of B1-B6, the wireless power receiverincludes an auxiliary rectifier, coupled to the antenna that receivessome of the RF signals. Furthermore, introducing the impedance mismatchbetween the wireless power receiver and the wireless power transmitterincludes adjusting a load of the auxiliary rectifier.

(B8) In some embodiments of B7, the wireless power receiver includes anauxiliary matching network coupled to and positioned between the antennaand the auxiliary rectifier. Furthermore, adjusting the load of theauxiliary rectifier causes an impedance mismatch between the auxiliarymatching network of the wireless power receiver and the wireless powertransmitter, which results the portion of the RF signals being reflectedby the antenna.

(B9) In some embodiments of B7, the wireless power receiver includes aswitch coupled to a load-adjusting mechanism, and the load-adjustingmechanism is coupled to the auxiliary rectifier. Moreover, the togglingthe switch, which causes a change within the load-adjusting mechanismthat produces a change in the load of the receiver, which results in theimpedance mismatch between the wireless power receiver and the wirelesspower transmitter.

(B10) In another aspect, a wireless power receiver (e.g., receiver 120,FIG. 3) is provided. In some embodiments, the wireless power receiverincludes: an antenna, a rectifier coupled to the antenna, a switchcoupled to the rectifier, the switch being configured to create animpedance mismatch or match before an input of the rectifier, one ormore processors; and memory storing one or more programs, which whenexecuted by the one or more processors cause the transmitter to performthe method described in any one of B1-B9.

(B11) In yet another aspect, a wireless power receiver is provided andthe wireless power receiver (e.g., receiver 120, FIG. 3) includes meansfor performing the method described in any one of B1-B9.

(B12) In still another aspect, a non-transitory computer-readablestorage medium is provided. The non-transitory computer-readable storagemedium stores executable instructions that, when executed by thewireless power receiver with one or more processors/cores, cause thewireless power receiver to perform the method described in any one ofB1-B9.

(C1) In yet another aspect, a method of power surge protection for awireless power receiver is performed. In some embodiments, this methodis performed at a wireless power receiver that includes: (i) an antenna,(ii) a rectifier coupled to the antenna, and (iii) a switch coupled tothe rectifier, the switch configured to create an impedance mismatch ormatch before an input of the rectifier. Further, the method includes,while the switch is in a default-closed state that grounds the switchand creates an impedance mismatch before an input of the rectifier: (i)receiving, by the antenna of the wireless power receiver, radiofrequency (RF) signals as an alternating current, whereby a firstportion of the alternating current is reflected away from the input ofthe rectifier due to the impedance mismatch between the wireless powerreceiver and the wireless power transmitter, and a second portion of thealternating current flows through the switch and to ground, and (ii)while the switch is in an open state that creates an impedance matchbetween the wireless power receiver and the wireless power transmitterat the input of the rectifier: the first portion of the alternatingcurrent flows through the input of the rectifier, allowing the firstportion of the alternating current to be converted into direct currentthat is used to charge or power a wireless electronic device. Moreover,the second portion of the alternating current flows through the switchand to the input of the rectifier, allowing the second portion of thealternating current to be converted into direct current that is used tocharge or power a wireless electronic device.

(C2) In some embodiments of C1, a negative voltage generator is placedto drive the switch. For example, the negative voltage generator may beplaced before the switch to drive the switch.

(C3) In some embodiments of any of C1-C2, the switch transitions fromthe default-closed state to the open state gradually over a period oftime, and during the period of time, a part of the first portion of thealternating current continues to be reflected away from the input of therectifier.

(C4) In some embodiments of C3, the switch transitions fromdefault-closed to open state by using a Gallium Nitride (GaN) switch ora depletion mode metal oxide semiconductor (MOS) switch.

(C5) In some embodiments of C3, the method also includes, dynamicallyadjusting the period of time based on a detected voltage of thealternating current.

(C6) In some embodiments of C5, dynamically adjusting includes reducingthe period of time based on a determination that the detected voltagedoes not satisfy a defined threshold value.

(C7) In some embodiments of C5, dynamically adjusting includesincreasing the period of time based on a determination that the detectedvoltage satisfies a defined threshold value.

(C8) In some embodiments of any of C1-C7, the switch has a voltagethreshold that is met before it enters the open fully open.

(C9) In some embodiments of C8, the voltage threshold is zero volts.

(C10) In some embodiments of any of C1-C9, the method further includes,while the switch is in the open state, ceasing to receive the RF signalsby the antenna of the wireless power receiver. Ceasing to receive the RFsignals causes the switch to transition back to the default-closed statefrom the open state.

(C11) In some embodiments of any of C1-C10, the wireless power receiverincludes a coupling mechanism that is coupled to the antenna, thecoupling mechanism including a first output and a second output. Thefirst output of the coupling mechanism is coupled to the rectifier andthe second output of the coupling mechanism is coupled to the switch.

(C12) In some embodiments of C11, the coupling mechanism partitions thealternating current. Further, the coupling mechanism: (i) directs afirst portion of the alternating current to the first output of thecoupling mechanism and (ii) directs a second portion of the alternatingcurrent to the second output of the coupling mechanism.

(C13) In some embodiments of C1-C12, the switch is coupled to an outputof the rectifier.

(C14) In some embodiments of C1-C12, wherein the wireless power receiveralso includes a matching network having (i) an input coupled to thefirst output of the coupling mechanism and (ii) an output coupled to therectifier.

(C15) In some embodiments of C14, the switch is coupled to the matchingnetwork and the rectifier.

(C16) In another aspect, a wireless power receiver (e.g., receiver 120,FIG. 3) is provided. In some embodiments, the wireless power receiverincludes: an antenna, a rectifier coupled to the antenna, a switchcoupled to the rectifier, the switch being configured to create animpedance mismatch or match before an input of the rectifier, one ormore processors; and memory storing one or more programs, which whenexecuted by the one or more processors cause the transmitter to performthe method described in any one of C1-C15.

(C17) In yet another aspect, a wireless power receiver is provided andthe receiver (e.g., receiver 120, FIG. 3) includes means for performingthe method described in any one of C1-C15.

(C18) In still another aspect, a non-transitory computer-readablestorage medium is provided. The non-transitory computer-readable storagemedium stores executable instructions that, when executed by thewireless power receiver with one or more processors/cores, cause thewireless power receiver to perform the method described in any one ofC1-C15.

Note that the various embodiments described above can be combined withany other embodiments described herein. The features and advantagesdescribed in the specification are not all inclusive and, in particular,many additional features and advantages will be apparent to one ofordinary skill in the art in view of the drawings, specification, andclaims. Moreover, it should be noted that the language used in thespecification has been principally selected for readability andinstructional purposes, and not intended to circumscribe or limit theinventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the present disclosure can be understood in greater detail, amore particular description may be had by reference to the features ofvarious embodiments, some of which are illustrated in the appendeddrawings. The appended drawings, however, merely illustrate pertinentfeatures of the present disclosure and are therefore not to beconsidered limiting, for the description may admit to other effectivefeatures.

FIG. 1A is a block diagram of an RF wireless power transmission system,in accordance with some embodiments.

FIG. 1B is another block diagram of an RF wireless power transmissionsystem, in accordance with some embodiments.

FIG. 1C is a block diagram showing components of an example RF chargingpad that includes an RF power transmitter integrated circuit and antennazones, in accordance with some embodiments.

FIG. 1D is a block diagram showing components of an example RF chargingpad that includes an RF power transmitter integrated circuit coupled toa switch, in accordance with some embodiments.

FIG. 2 is a block diagram showing components of an example RFtransmitter, in accordance with some embodiments.

FIG. 3 is a block diagram showing components of an example RF receiver,in accordance with some embodiments.

FIG. 4A is a circuit schematic illustrating an example RF receiver withtwo rectifiers for detecting changes in received RF power, in accordancewith some embodiments.

FIG. 4B is a circuit schematic illustrating points at which a couplingmechanism may be added to the circuit, in accordance with someembodiments.

FIG. 4C illustrates circuit schematics for exemplary couplingmechanisms, in accordance with some embodiments, in accordance with someembodiments.

FIG. 4D illustrates circuit schematics for exemplary rectifiers, inaccordance with some embodiments, in accordance with some embodiments.

FIG. 4E illustrates a circuit schematics for detecting when RF power isno longer received at the antenna, in accordance with some embodiments.

FIG. 4F illustrates circuit schematics of simplified rectifiers, inaccordance with some embodiments.

FIG. 5A depicts a circuit schematic illustrating a system for protectingsensitive electrical components from power surges, in accordance withsome embodiments.

FIG. 5B depicts a circuit schematic illustrating points at which acoupling mechanism may be added to the circuit, in accordance with someembodiments.

FIG. 6A depicts a circuit schematic illustrating a receiver capable ofcommunicating with a transmitter, in accordance with some embodiments.

FIG. 6B depicts a circuit schematic illustrating points at which acoupling mechanism may be added to the circuit, in accordance with someembodiments.

FIG. 6C illustrates is a circuit schematic illustrating exemplarycomponents for adjusting the load of a rectifier to cause an impedancemismatch, in accordance with some embodiments.

FIG. 7 is a flow diagram showing a process of a receiver communicatingwith a transmitter, in accordance with some embodiments.

In accordance with common practice, the various features illustrated inthe drawings may not be drawn to scale. Accordingly, the dimensions ofthe various features may be arbitrarily expanded or reduced for clarity.In addition, some of the drawings may not depict all of the componentsof a given system, method or device. Finally, like reference numeralsmay be used to denote like features throughout the specification andfigures.

DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings. In the following detaileddescription, numerous specific details are set forth in order to providea thorough understanding of the various described embodiments. However,it will be apparent to one of ordinary skill in the art that the variousdescribed embodiments may be practiced without these specific details.In other instances, well-known methods, procedures, components,circuits, and networks have not been described in detail so as not tounnecessarily obscure aspects of the embodiments.

FIG. 1A is a block diagram of components of wireless power transmissionenvironment 100, in accordance with some embodiments. Wireless powertransmission environment 100 includes, for example, transmitters 102(e.g., transmitters 102 a, 102 b . . . 102 n) and one or more receivers120 (e.g., receivers 120 a, 120 b . . . 120 n). In some embodiments,each respective wireless power transmission environment 100 includes anumber of receivers 120, each of which is associated with a respectiveelectronic device 122. In some instances, the transmitter 102 isreferred to herein as a “wireless-power-transmitting device” or a“wireless power transmitter.” Additionally, in some instances, thereceiver 120 is referred to herein as a “wireless-power-receivingdevice” or a “wireless power receiver.”

An example transmitter 102 (e.g., transmitter 102 a) includes, forexample, one or more processor(s) 104, a memory 106, one or more antennaarrays 110, one or more communications components 112 (also referred toherein as a “wireless communications radio,” a “communications radio” orsimply a “radio”), and/or one or more transmitter sensors 114. In someembodiments, these components are interconnected by way of acommunications bus 107. References to these components of transmitters102 cover embodiments in which one or more of these components (andcombinations thereof) are included. The components are discussed infurther detail below with reference to FIG. 2.

In some embodiments, a single processor 104 (e.g., processor 104 oftransmitter 102 a) executes software modules for controlling multipletransmitters 102 (e.g., transmitters 102 b . . . 102 n). In someembodiments, a single transmitter 102 (e.g., transmitter 102 a) includesmultiple processors 104, such as one or more transmitter processors(configured to, e.g., control transmission of signals 116 by antennaarray 110), one or more communications component processors (configuredto, e.g., control communications transmitted by communications component112 and/or receive communications by way of communications component112) and/or one or more sensor processors (configured to, e.g., controloperation of transmitter sensor 114 and/or receive output fromtransmitter sensor 114).

The wireless power receiver 120 receives power transmission signals 116and/or communication signals 118 transmitted by transmitters 102. Insome embodiments, the receiver 120 includes one or more antennas 124(e.g., an antenna array including multiple antenna elements), powerconverter 126, receiver sensor 128, and/or other components or circuitry(e.g., processor(s) 140, memory 142, and/or communication component(s)144. In some embodiments, these components are interconnected by way ofa communications bus 146. References to these components of receiver 120cover embodiments in which one or more of these components (andcombinations thereof) are included.

The receiver 120 converts energy from received signals 116 (alsoreferred to herein as RF power transmission signals, or simply, RFsignals, RF waves, power waves, or power transmission signals) intoelectrical energy to power and/or charge electronic device 122. Forexample, the receiver 120 uses the power converter 126 to convert energyderived from power waves 116 to alternating current (AC) electricity ordirect current (DC) electricity to power and/or charge the electronicdevice 122. Non-limiting examples of the power converter 126 includerectifiers, rectifying circuits, voltage conditioners, among suitablecircuitry and devices.

In some embodiments, the receiver 120 is a standalone device that isdetachably coupled to one or more electronic devices 122. For example,the electronic device 122 has processor(s) 132 for controlling one ormore functions of the electronic device 122, and the receiver 120 hasprocessor(s) 140 for controlling one or more functions of the receiver120.

In some embodiments, the receiver 120 is a component of the electronicdevice 122. For example, processors 132 control functions of theelectronic device 122 and the receiver 120. In addition, in someembodiments, the receiver 120 includes one or more processors 140, whichcommunicates with processors 132 of the electronic device 122.

In some embodiments, the electronic device 122 includes one or moreprocessors 132, memory 134, one or more communication components 136,and/or one or more batteries 130. In some embodiments, these componentsare interconnected by way of a communications bus 138. In someembodiments, communications between electronic device 122 and receiver120 occur via communications component(s) 136 and/or 144. In someembodiments, communications between the electronic device 122 and thereceiver 120 occur via a wired connection between communications bus 138and communications bus 146. In some embodiments, the electronic device122 and the receiver 120 share a single communications bus.

In some embodiments, the receiver 120 receives one or more power waves116 directly from the transmitter 102 (e.g., via one or more antennas124). In some embodiments, the receiver 120 harvests power waves fromone or more pockets of energy created by one or more power waves 116transmitted by the transmitter 102. In some embodiments, the transmitter102 is a near-field transmitter that transmits the one or more powerwaves 116 within a near-field distance (e.g., less than approximatelysix inches away from the transmitter 102). In other embodiments, thetransmitter 102 is a far-field transmitter that transmits the one ormore power waves 116 within a far-field distance (e.g., more thanapproximately six inches away from the transmitter 102).

After the power waves 116 are received and/or energy is harvested fromthem, circuitry (e.g., integrated circuits, amplifiers, rectifiers,and/or voltage conditioner) of the receiver 120 converts the energy ofthe power waves to usable power (i.e., electricity), which powers theelectronic device 122 and/or is stored to battery 130 of the electronicdevice 122. In some embodiments, a rectifying circuit of the receiver120 translates the electrical energy from AC to DC for use by theelectronic device 122. In some embodiments, a voltage conditioningcircuit increases or decreases the voltage of the electrical energy asrequired by the electronic device 122. In some embodiments, anelectrical relay conveys electrical energy from the receiver 120 to theelectronic device 122.

In some embodiments, the electronic device 122 obtains power frommultiple transmitters 102 and/or using multiple receivers 120. In someembodiments, the wireless power transmission environment 100 includes aplurality of electronic devices 122, each having at least one respectivereceiver 120 that is used to harvest power waves from the transmitters102 into power for charging the electronic devices 122.

In some embodiments, the one or more transmitters 102 adjust values ofone or more characteristics (e.g., waveform characteristics, such asphase, gain, direction, amplitude, polarization, and/or frequency) ofpower waves 116. For example, a transmitter 102 selects a subset of oneor more antenna elements of antenna array 110 to initiate transmissionof power waves 116, cease transmission of power waves 116, and/or adjustvalues of one or more characteristics used to transmit power waves 116.In some embodiments, the one or more transmitters 102 adjust power waves116 such that trajectories of power waves 116 converge at apredetermined location within a transmission field (e.g., a location orregion in space), resulting in controlled constructive or destructiveinterference patterns. The transmitter 102 may adjust values of one ormore characteristics for transmitting the power waves 116 to account forchanges at the wireless power receiver that may negatively impacttransmission of the power waves 116.

Note that, in some embodiments, the transmitter 102 utilizes beamformingtechniques to wirelessly transfer power to a receiver 120, while inother embodiments, the transmitter 102 does not utilize beamformingtechniques to wirelessly transfer power to a receiver 120 (e.g., incircumstances in which no beamforming techniques are used, thetransmitter controller IC 160 discussed below might be designed withoutany circuitry to allow for use of beamforming techniques, or thatcircuitry may be present, but might be deactivated to eliminate anybeamforming control capability).

In some embodiments, respective antenna arrays 110 of the one or moretransmitters 102 may include a set of one or more antennas configured totransmit the power waves 116 into respective transmission fields of theone or more transmitters 102. Integrated circuits (FIG. 1C) of therespective transmitter 102, such as a controller circuit (e.g., a radiofrequency integrated circuit (RFIC)) and/or waveform generator, maycontrol the behavior of the antennas. For example, based on theinformation received from the receiver 120 by way of the communicationsignal 118, a controller circuit (e.g., processor 104 of the transmitter102, FIG. 1A) may determine values of the waveform characteristics(e.g., amplitude, frequency, trajectory, direction, phase, polarization,among other characteristics) of power waves 116 that would effectivelyprovide power to the receiver 120, and in turn, the electronic device122. The controller circuit may also identify a subset of antennas fromthe antenna arrays 110 that would be effective in transmitting the powerwaves 116. In some embodiments, a waveform generator circuit (not shownin FIG. 1A) of the respective transmitter 102 coupled to the processor104 may convert energy and generate the power waves 116 having thespecific values for the waveform characteristics identified by theprocessor 104/controller circuit, and then provide the power waves tothe antenna arrays 110 for transmission.

In some embodiments, the communications component 112 transmitscommunication signals 118 by way of a wired and/or wirelesscommunication connection to the receiver 120. In some embodiments, thecommunications component 112 generates communication signals 118 usedfor triangulation of the receiver 120 (e.g., test signals). In someembodiments, the communication signals 118 are used to conveyinformation between the transmitter 102 and receiver 120 for adjustingvalues of one or more waveform characteristics used to transmit thepower waves 116 (e.g., convey amounts of power derived from RF testsignals). In some embodiments, the communication signals 118 includeinformation related to status, efficiency, user data, power consumption,billing, geo-location, and other types of information.

In some embodiments, the communications component 112 transmitscommunication signals 118 to the receiver 120 by way of the electronicdevice 122a. For example, the communications component 112 may conveyinformation to the communications component 136 of the electronic device122 a, which the electronic device 122a may in turn convey to thereceiver 120 (e.g., via bus 138).

In some embodiments, the communications component 112 includes acommunications component antenna for communicating with the receiver 120and/or other transmitters 102 (e.g., transmitters 102 b through 102 n).In some embodiments, these communication signals 118 are sent using afirst channel (e.g., a first frequency band) that is independent anddistinct from a second channel (e.g., a second frequency band distinctfrom the first frequency band) used for transmission of the power waves116.

In some embodiments, the receiver 120 includes a receiver-sidecommunications component 144 configured to communicate various types ofdata with one or more of the transmitters 102, through a respectivecommunication signal 118 generated by the receiver-side communicationscomponent (in some embodiments, a respective communication signal 118 isreferred to as an advertising signal). The data may include locationindicators for the receiver 120 and/or electronic device 122, a powerstatus of the device 122, status information for the receiver 120,status information for the electronic device 122, status informationabout the power waves 116, and/or status information for pockets ofenergy. In other words, the receiver 120 may provide data to thetransmitter 102, by way of the communication signal 118, regarding thecurrent operation of the system 100, including: information identifyinga present location of the receiver 120 or the device 122, an amount ofenergy (i.e., usable power) received by the receiver 120, and an amountof power received and/or used by the electronic device 122, among otherpossible data points containing other types of information.

In some embodiments, the data contained within communication signals 118is used by the electronic device 122, the receiver 120, and/or thetransmitters 102 for determining adjustments to values of one or morewaveform characteristics used by the antenna array 110 to transmit thepower waves 116. Using a communication signal 118, the transmitter 102communicates data that is used, e.g., to identify receivers 120 within atransmission field, identify electronic devices 122, determine safe andeffective waveform characteristics for power waves, and/or hone theplacement of pockets of energy. In some embodiments, the receiver 120uses a communication signal 118 to communicate data for, e.g., alertingtransmitters 102 that the receiver 120 has entered or is about to entera transmission field(e.g., come within wireless-power-transmission rangeof a transmitter 102), provide information about the electronic device122, provide user information that corresponds to the electronic device122, indicate the effectiveness of received power waves 116, and/orprovide updated characteristics or transmission parameters that the oneor more transmitters 102 use to adjust transmission of the power waves116.

In some embodiments, the receiver 120 does not include a distinctcommunications component 144. Rather, the receiver 120 is configured toreflect RF signals transmitted by the transmitter 102 at the one or moreantennas 124 and, importantly, modulate the reflected RF signals toconvey data (or a message) to transmitter 102. In such embodiments, thetransmitter 102 may also lack a distinct communications component.Instead, the transmitter 102 may receive the reflected RF signals at theone or more antenna arrays 110, and the transmitter 102 may demodulatethe reflected RF signals in order to interpret them. Reflecting RFsignals by the receiver 120 is discussed in further detail below withreference to FIGS. 6A-6C.

In some embodiments, transmitter sensor 114 and/or receiver sensor 128detect and/or identify conditions of the electronic device 122, thereceiver 120, the transmitter 102, and/or a transmission field. In someembodiments, data generated by the transmitter sensor 114 and/orreceiver sensor 128 is used by the transmitter 102 to determineappropriate adjustments to values of one or more waveformcharacteristics used to transmit the power waves 116. Data fromtransmitter sensor 114 and/or receiver sensor 128 received by thetransmitter 102 includes, e.g., raw sensor data and/or sensor dataprocessed by a processor 104, such as a sensor processor. Processedsensor data includes, e.g., determinations based upon sensor dataoutput. In some embodiments, sensor data received from sensors that areexternal to the receiver 120 and the transmitters 102 is also used (suchas thermal imaging data, information from optical sensors, and others).

FIG. 1B is another block diagram of an RF wireless power transmissionsystem 150 in accordance with some embodiments. In some embodiments, theRF wireless power transmission system 150 includes a far-fieldtransmitter (not shown). In some embodiments, the RF wireless powertransmission system 150 includes a RF charging pad 151 (also referred toherein as a near-field (NF) charging pad 151 or RF charging pad 151).The RF charging pad 151 may be an example of the transmitter 102 in FIG.1A.

In some embodiments, the RF charging pad 151 includes an RF powertransmitter integrated circuit 160 (described in more detail below). Insome embodiments, the RF charging pad 151 includes one or more optionalcommunications components 112 (e.g., wireless communication components,such as WI-FI or BLUETOOTH radios). Alternatively, in some embodiments,the RF charging pad 151 does not include the optional communicationscomponents 112. In such embodiments, the RF charging pad 151 includesalternative means for communicating with other devices (e.g., the RFcharging pad 151 receives and interprets RF signals reflected by areceiver 120). In some embodiments, the RF charging pad 151 alsoconnects to one or more power amplifier units 108-1, . . . 108-n (PA orPA units) to control operation of the one or more power amplifier unitswhen they drive external power-transfer elements (e.g., antennas 290).In some embodiments, RF power is controlled and modulated at the RFcharging pad 151 via switch circuitry as to enable the RF wireless powertransmission system to send RF power to one or more wireless receivingdevices via the TX antenna array 110.

The optional communication component(s) 112 enable communication betweenthe RF charging pad 151 and one or more communication networks, and arediscussed in further detail above with reference to FIG. 1A. In someinstances, the communication component(s) 112 are not able tocommunicate with wireless power receivers for various reasons, e.g.,because there is no power available for the communication component(s)to use for the transmission of data signals or because the wirelesspower receiver 120 itself does not actually include any communicationcomponent of its own. As such, it is important to design near-fieldcharging pads that are still able to uniquely identify different typesof devices and, when a wireless power receiver is detected, figure outif that wireless power receiver is authorized to receive wireless power.

FIG. 1C is a block diagram of the RF power transmitter integratedcircuit 160 (the “integrated circuit”) in accordance with someembodiments. In some embodiments, the integrated circuit 160 includes aCPU subsystem 170, an external device control interface, an RFsubsection for DC to RF power conversion, and analog and digital controlinterfaces interconnected via an interconnection component, such as abus or interconnection fabric block 171. In some embodiments, the CPUsubsystem 170 includes a microprocessor unit (CPU) 202 with relatedRead-Only-Memory (ROM) 172 for device program booting via a digitalcontrol interface, e.g. an I²C port, to an external FLASH containing theCPU executable code to be loaded into the CPU Subsystem Random AccessMemory (RAM) 174 (e.g., memory 206, FIG. 2A) or executed directly fromFLASH. In some embodiments, the CPU subsystem 170 also includes anencryption module or block 176 to authenticate and secure communicationexchanges with external devices, such as wireless power receivers thatattempt to receive wirelessly delivered power from the RF charging pad150.

In some embodiments, the RF IC 160 also includes (or is in communicationwith) a power amplifier controller IC 161A (PA IC) that is responsiblefor controlling and managing operations of a power amplifier (ormultiple power amplifiers), including for reading measurements ofimpedance at various measurement points within the power amplifier 108,whereby these measurements are used, in some instances, for detecting offoreign objects. The PA IC 161A may be on the same integrated circuit atthe RF IC 160, or may be on its on integrated circuit that is separatefrom (but still in communication with) the RF IC 160. Additional detailsregarding the architecture and operation of the PA IC are provided inU.S. Provisional Application No. ______ (Attorney Docket No.117685-5197-PR), the disclosure of which is incorporated by referenceherein in its entirety.

In some embodiments, executable instructions running on the CPU (such asthose shown in the memory 106 in FIG. 2 and described below) are used tomanage operation of the RF charging pad 151 and to control externaldevices through a control interface, e.g., SPI control interface 175,and the other analog and digital interfaces included in the RF powertransmitter integrated circuit 160. In some embodiments, the CPUsubsystem also manages operation of the RF subsection of the RF powertransmitter integrated circuit 160, which includes an RF localoscillator (LO) 177 and an RF transmitter (TX) 178. In some embodiments,the RF LO 177 is adjusted based on instructions from the CPU subsystem170 and is thereby set to different desired frequencies of operation,while the RF TX converts, amplifies, modulates the RF output as desiredto generate a viable RF power level.

In the descriptions that follow, various references are made to antennazones and power-transfer zones, which terms are used synonymously inthis disclosure. In some embodiments the antenna/power-transfer zonesmay include antenna elements that transmit propagating radio frequencywaves but, in other embodiments, the antenna/power transfer zones mayinstead include capacitive charging couplers that convey electricalsignals but do not send propagating radio frequency waves.

In some embodiments, the RF power transmitter integrated circuit 160provides the viable RF power level (e.g., via the RF TX 178) to anoptional beamforming integrated circuit (IC) 109, which then providesphase-shifted signals to one or more power amplifiers 108. In someembodiments, the beamforming IC 109 is used to ensure that powertransmission signals sent using two or more antennas 210 (e.g., eachantenna 210 may be associated with a different antenna zone 290 or mayeach belong to a single antenna zone 290) to a particular wireless powerreceiver are transmitted with appropriate characteristics (e.g., phases)to ensure that power transmitted to the particular wireless powerreceiver is maximized (e.g., the power transmission signals arrive inphase at the particular wireless power receiver). In some embodiments,the beamforming IC 109 forms part of the RF power transmitter IC 160. Inembodiments in which capacitive couplers (e.g., capacitive chargingcouplers 244) are used as the antennas 210, then optional beamforming IC109 may not be included in the RF power transmitter integrated circuit160.

In some embodiments, the RF power transmitter integrated circuit 160provides the viable RF power level (e.g., via the RF TX 178) directly tothe one or more power amplifiers 108 and does not use the beamforming IC109 (or bypasses the beamforming IC if phase-shifting is not required,such as when only a single antenna 210 is used to transmit powertransmission signals to a wireless power receiver). In some embodiments,the PA IC 161A receives the viable RF power level and provides that tothe one or more power amplifiers 108.

In some embodiments, the one or more power amplifiers 108 then provideRF signals to the antenna zones 290 (also referred to herein as“power-transfer zones”) for transmission to wireless power receiversthat are authorized to receive wirelessly delivered power from the RFcharging pad 151. In some embodiments, each antenna zone 290 is coupledwith a respective PA 108 (e.g., antenna zone 290-1 is coupled with PA108-1 and antenna zone 290-N is coupled with PA 108-N). In someembodiments, multiple antenna zones are each coupled with a same set ofPAs 108 (e.g., all PAs 108 are coupled with each antenna zone 290).Various arrangements and couplings of PAs 108 to antenna zones 290 allowthe RF charging pad 151 to sequentially or selectively activatedifferent antenna zones in order to determine the most efficient antennazone 290 to use for transmitting wireless power to a wireless powerreceiver. In some embodiments, the one or more power amplifiers 108 arealso in communication with the CPU subsystem 170 to allow the CPU 202 tomeasure output power provided by the PAs 108 to the antenna zones 110 ofthe RF charging pad 151.

FIG. 1C also shows that, in some embodiments, the antenna zones 290 ofthe RF charging pad 151 may include one or more antennas 210A-N. In someembodiments, each antenna zone of the plurality of antenna zones 290includes one or more antennas 210 (e.g., antenna zone 290-1 includes oneantenna 210-A and antenna zones 290-N includes multiple antennas 210).In some embodiments, a number of antennas included in each of theantenna zones is dynamically defined based on various parameters, suchas a location of a wireless power receiver on the RF charging pad 151.In some embodiments, each antenna zone 290 may include antennas ofdifferent types, while in other embodiments each antenna zone 290 mayinclude a single antenna of a same type, while in still otherembodiments, the antennas zones may include some antenna zones thatinclude a single antenna of a same type and some antenna zones thatinclude antennas of different types. In some embodiments theantenna/power-transfer zones may also or alternatively includecapacitive charging couplers that convey electrical signals but do notsend propagating radio frequency waves.

In some embodiments, the RF charging pad 151 may also include atemperature monitoring circuit that is in communication with the CPUsubsystem 170 to ensure that the RF charging pad 151 remains within anacceptable temperature range. For example, if a determination is madethat the RF charging pad 151 has reached a threshold temperature, thenoperation of the RF charging pad 151 may be temporarily suspended untilthe RF charging pad 151 falls below the threshold temperature.

By including the components shown for RF power transmitter circuit 160(FIG. 1C) on a single chip, such transmitter chips are able to manageoperations at the transmitter chips more efficiently and quickly (andwith lower latency), thereby helping to improve user satisfaction withthe charging pads that are managed by these transmitter chips. Forexample, the RF power transmitter circuit 160 is cheaper to construct,has a smaller physical footprint, and is simpler to install.

FIG. 1D is a block diagram of a charging pad 294 in accordance with someembodiments. The charging pad 294 is an example of the charging pad 151(FIG. 1B), however, one or more components included in the charging pad151 are not included in the charging pad 294 for ease of discussion andillustration.

The charging pad 294 includes an RF power transmitter integrated circuit160, one or more power amplifiers 108, a PA IC 161A (which may be on thesame or a separate IC from the RF power transmitter IC 160), and atransmitter antenna array 290 having multiple antenna zones. Each ofthese components is described in detail above with reference to FIGS.1A-1C. Additionally, the charging pad 294 includes a switch 295 (i.e.,transmitter-side switch), positioned between the power amplifiers 108and the antenna array 290, having a plurality of switches 297-A, 297-B,. . . 297-N. The switch 295 is configured to switchably connect one ormore power amplifiers 108 with one or more antenna zones of the antennaarray 290 in response to control signals provided by the RF powertransmitter integrated circuit 160.

To accomplish the above, each switch 297 is coupled with (e.g., providesa signal pathway to) a different antenna zone of the antenna array 290.For example, switch 297-A may be coupled with a first antenna zone 290-1(FIG. 1C) of the antenna array 290, switch 297-B may be coupled with asecond antenna zone 290-2 of the antenna array 290, and so on. Each ofthe plurality of switches 297-A, 297-B, . . . 297-N, once closed,creates a unique pathway between a respective power amplifier 108 (ormultiple power amplifiers 108) and a respective antenna zone of theantenna array 290. Each unique pathway through the switch 295 is used toselectively provide RF signals to specific antenna zones of the antennaarray 290. It is noted that two or more of the plurality of switches297-A, 297-B, . . . 297-N may be closed at the same time, therebycreating multiple unique pathways to the antenna array 290 that may beused simultaneously.

In some embodiments, the RF power transmitter integrated circuit 160 (orthe PA IC 161A, or both) is (are) coupled to the switch 295 and isconfigured to control operation of the plurality of switches 297-A,297-B, . . . 297-N (illustrated as a “control out” signal in FIGS. 1Band 1D). For example, the RF power transmitter integrated circuit 160may close a first switch 297-A while keeping the other switches open. Inanother example, the RF power transmitter integrated circuit 160 mayclose a first switch 297-A and a second switch 297-B, and keep the otherswitches open (various other combinations and configuration arepossible). Moreover, the RF power transmitter integrated circuit 160 iscoupled to the one or more power amplifiers 108 and is configured togenerate a suitable RF signal (e.g., the “RF Out” signal) and providethe RF signal to the one or more power amplifiers 108. The one or morepower amplifiers 108, in turn, are configured to provide the RF signalto one or more antenna zones of the antenna array 290 via the switch295, depending on which switches 297 in the switch 295 are closed by theRF power transmitter integrated circuit 160.

In some embodiments, the charging pad is configured to transmit testpower transmission signals and/or regular power transmission signalsusing different antenna zones, e.g., depending on a location of areceiver on the charging pad. Accordingly, when a particular antennazone is selected for transmitting test signals or regular power signals,a control signal is sent to the switch 295 from the RF power transmitterintegrated circuit 160 to cause at least one switch 297 to close. Indoing so, an RF signal from at least one power amplifier 108 can beprovided to the particular antenna zone using a unique pathway createdby the now-closed at least one switch 297.

In some embodiments, the switch 295 may be part of (e.g., internal to)the antenna array 290. Alternatively, in some embodiments, the switch295 is separate from the antenna array 290 (e.g., the switch 295 may bea distinct component, or may be part of another component, such as thepower amplifier(s) 108). It is noted that any switch design capable ofaccomplishing the above may be used, and the design of the switch 295illustrated in FIG. 1D is merely one example.

FIG. 2 is a block diagram illustrating a representative transmitterdevice 102 (also sometimes referred to herein as a transmitter 102, awireless power transmitter 102, and a wireless-power-transmitting device102) in accordance with some embodiments. In some embodiments, thetransmitter device 102 includes one or more processors 104 (e.g., CPUs,ASICs, FPGAs, microprocessors, and the like), one or more optionalcommunication components 112 (e.g., radios), memory 106, one or moreantennas 110, and one or more communication buses 108 forinterconnecting these components (sometimes called a chipset). In someembodiments, the transmitter device 102 includes one or more sensors 114as described above with reference to FIG. 1A. In some embodiments, thetransmitter device 102 includes one or more output devices such as oneor more indicator lights, a sound card, a speaker, a small display fordisplaying textual information and error codes, etc. In someembodiments, the transmitter device 102 includes a location detectiondevice, such as a GPS (global positioning satellite) or othergeo-location receiver, for determining the location of the transmitterdevice 102.

The communication components 112 enable communication between thetransmitter 102 and the receiver 120 (e.g., one or more communicationnetworks). In some embodiments, the communication components 112include, e.g., hardware capable of data communications using any of avariety of wireless protocols (e.g., IEEE 802.15.4, Wi-Fi, ZigBee,6LoWPAN, Thread, Z-Wave, Bluetooth Smart, ISA100.11a, WirelessHART,MiWi, etc.) wired protocols (e.g., Ethernet, HomePlug, etc.), and/or anyother suitable communication protocol, including communication protocolsnot yet developed as of the filing date of this document.

The memory 106 includes high-speed random access memory, such as DRAM,SRAM, DDR SRAM, or other random access solid state memory devices; and,optionally, includes non-volatile memory, such as one or more magneticdisk storage devices, one or more optical disk storage devices, one ormore flash memory devices, or one or more other non-volatile solid statestorage devices. The memory 106, or alternatively the non-volatilememory within memory 106, includes a non-transitory computer-readablestorage medium. In some embodiments, the memory 106, or thenon-transitory computer-readable storage medium of the memory 106,stores the following programs, modules, and data structures, or a subsetor superset thereof:

-   -   operating logic 216 including procedures for handling various        basic system services and for performing hardware dependent        tasks;    -   communication module 218 for coupling to and/or communicating        with remote devices (e.g., remote sensors, transmitters,        receivers, servers, etc.), in conjunction with communication        component(s) 112 and/or antenna(s) 110;    -   sensor module 220 for obtaining and processing sensor data        (e.g., in conjunction with sensor(s) 114) to, for example,        determine the presence, velocity, and/or positioning of object        in the vicinity of the transmitter 102;    -   optimal phase setting module 222 for determining an optimal        phase antenna for respective antennas in the transmitter's        antenna array 110. In some embodiments, as discussed below with        reference to FIGS. 5A-5C, the optimal phase setting module 222        determines the optimal phase setting using either a binary        search method or a least squares method, or some combination        thereof;    -   power wave generating module 224 for generating and transmitting        (e.g., in conjunction with antenna(s) 110) power waves. In some        embodiments, the power wave generating module 224 is associated        with (or includes) the optimal phase setting module 222 is used        to determine the optimal phase; and    -   database 226, including but not limited to:        -   sensor information 228 for storing and managing data            received, detected, and/or transmitted by one or more            sensors (e.g., sensors 114 and/or one or more remote            sensors);        -   test phases 230 for storing and managing predetermined test            phases of test signals transmitted by the power wave            generating module 224. In some embodiments, as discussed            below with reference to FIGS. 5A-5C, the test phases are            separated by a predetermined interval corresponding to known            characteristics of a pure sinusoidal wave;        -   optimal phases 232 for storing and managing optimal antenna            phases determined by the optimal phase setting module 222            for one or more antennas 110; and        -   communication protocol information 234 for storing and            managing protocol information for one or more protocols            (e.g., custom or standard wireless protocols, such as            ZigBee, Z-Wave, etc., and/or custom or standard wired            protocols, such as Ethernet).

Each of the above-identified elements (e.g., modules stored in memory106 of the transmitter 102) is optionally stored in one or more of thepreviously mentioned memory devices, and corresponds to a set ofinstructions for performing the function(s) described above. The aboveidentified modules or programs (e.g., sets of instructions) need not beimplemented as separate software programs, procedures, or modules, andthus various subsets of these modules are optionally combined orotherwise rearranged in various embodiments. In some embodiments, thememory 106, optionally, stores a subset of the modules and datastructures identified above. Furthermore, the memory 106, optionally,stores additional modules and data structures not described above, suchas a tracking module for tracking the movement and positioning ofobjects within a transmission field.

FIG. 3 is a block diagram illustrating a representative receiver device120 (also referred to herein as a receiver 120, a wireless powerreceiver 120, and a wireless-power-receiving device 120) in accordancewith some embodiments. In some embodiments, the receiver device 120includes one or more processors 140 (e.g., CPUs, ASICs, FPGAs,microprocessors, and the like), one or more optional communicationcomponents 144, memory 142, one or more antennas 124, power harvestingcircuitry 310, and one or more communication buses 308 forinterconnecting these components (sometimes called a chipset). In someembodiments, the receiver device 120 includes one or more sensors 128such as one or sensors described above with reference to FIG. 1A. Insome embodiments, the receiver device 120 includes an energy storagedevice 312 for storing energy harvested via the power harvestingcircuitry 310. In various embodiments, the energy storage device 312includes one or more batteries (e.g., battery 130, FIG. 1A), one or morecapacitors, one or more inductors, and the like.

As described above with reference to FIG. 1A, in some embodiments, thereceiver 120 is internally or externally connected to an electronicdevice (e.g., electronic device 122 a, FIG. 1A) via a connection 138(e.g., a bus). In some embodiments, the energy storage device 312 ispart of the electronic device.

In some embodiments, the power harvesting circuitry 310 includes one ormore rectifying circuits and/or one or more power converters. In someembodiments, the power harvesting circuitry 310 includes one or morecomponents (e.g., a power converter 126) configured to convert energyfrom power waves and/or energy pockets to electrical energy (e.g.,electricity). In some embodiments, the power harvesting circuitry 310 isfurther configured to supply power to a coupled electronic device (e.g.,an electronic device 122), such as a laptop or phone. In someembodiments, supplying power to a coupled electronic device includetranslating electrical energy from an AC form to a DC form (e.g., usableby the electronic device 122).

The communication component(s) 144 enable communication between thereceiver 120 and the transmitter 102 (e.g., via one or morecommunication networks). In some embodiments, the communicationcomponent(s) 144 include, e.g., hardware capable of data communicationsusing any of a variety of custom or standard wireless protocols (e.g.,IEEE 802.15.4, Wi-Fi, ZigBee, 6LoWPAN, Thread, Z-Wave, Bluetooth Smart,ISA100.11a, WirelessHART, MiWi, etc.) custom or standard wired protocols(e.g., Ethernet, HomePlug, etc.), and/or any other suitablecommunication protocol, including communication protocols not yetdeveloped as of the filing date of this document. In some embodiments,the receiver 120 may utilize a built-in communication component (e.g., aBluetooth radio) or an electronic device with which the receiver 120 iscoupled, and therefore, in these embodiments, the receiver 120 may notinclude its own communication component. In some other embodiments, thereceiver 120 does not include a distinct communication component 144.Rather, the receiver 120 may use an in-band communication technique tocommunicate with other devices, as explained below with reference toFIGS. 6A-6C and FIG. 7.

The memory 142 includes high-speed random access memory, such as DRAM,SRAM, DDR SRAM, or other random access solid state memory devices; and,optionally, includes non-volatile memory, such as one or more magneticdisk storage devices, one or more optical disk storage devices, one ormore flash memory devices, or one or more other non-volatile solid statestorage devices. The memory 142, or alternatively the non-volatilememory within memory 142, includes a non-transitory computer-readablestorage medium. In some embodiments, the memory 142, or thenon-transitory computer-readable storage medium of the memory 142,stores the following programs, modules, and data structures, or a subsetor superset thereof:

-   -   operating logic 314 including procedures for handling various        basic system services and for performing hardware dependent        tasks;    -   communication module 316 for coupling to and/or communicating        with remote devices (e.g., remote sensors, transmitters, other        receivers, servers, electronic devices, mapping memories, etc.)        in conjunction with the optional communication component(s) 144        and/or antenna(s) 124;    -   sensor module 318 for obtaining and processing sensor data        (e.g., in conjunction with sensor(s) 128) to, for example,        determine the presence, velocity, and/or positioning of the        receiver 120, a transmitter 102, or an object in the vicinity of        the receiver 120;    -   power receiving module 320 for receiving (e.g., in conjunction        with antenna(s) 124 and/or power harvesting circuitry 310) and        optionally converting (e.g., in conjunction with power        harvesting circuitry 310) the energy (e.g., to direct current);        transferring the energy to a coupled electronic device (e.g., an        electronic device 122); and optionally storing the energy (e.g.,        in conjunction with energy storage device 312)    -   power determining module 321 for determining (in conjunction        with operation of the power receiving module 320) an amount of        power received by the receiver based on energy extracted from        power waves (or RF test signals) and/or pockets or energy at        which the power waves converge (e.g., RF signals 116, FIG. 1A).        In some embodiments, as discussed below with reference to FIGS.        5A-5B, after determining an amount of power received by the        receiver, the receiver 120 transmits to the transmitter 102        information identifying the amount of power;    -   a switch module 330 for signaling when to open a switch of the        power harvesting circuity 310 in order to stop power surges from        damaging sensitive components. In some embodiments, as discussed        below with reference to FIGS. 5A-5B, the switch is a negative        voltage switch that is in a default-closed state;    -   A toggle module 332 for controlling the impedance mismatch in        the system, which in turn can cause a portion of the incoming        power to be reflected from the antenna of the wireless power        receiver. By modulating the amount of power reflected by the        antenna device can communicate with a wireless power transmitter        without needing a dedicate communication component (e.g., .,        IEEE 802.15.4, Wi-Fi, ZigBee, 6LoWPAN, Thread, Z-Wave, Bluetooth        Smart, ISA100.11a, WirelessHART, MiWi, etc.) wired protocols        (e.g., Ethernet, HomePlug, etc.). In some embodiments, as        discussed with reference to FIGS. 6A-6C below, when the toggle        602 toggles it causes the adjustable load 601 to change the        impedance of the receiver 120, which further causes incoming        power to be reflected at antenna 413; and    -   database 322, including but not limited to:        -   sensor information 324 for storing and managing data            received, detected, and/or transmitted by one or more            sensors (e.g., sensors 128 and/or one or more remote            sensors);        -   device settings 326 for storing and managing operational            settings for the receiver 120, a coupled electronic device            (e.g., an electronic device 122), and/or one or more remote            devices; and        -   communication protocol information 328 for storing and            managing protocol information for one or more protocols            (e.g., custom or standard wireless protocols, such as            ZigBee, Z-Wave, etc., and/or custom or standard wired            protocols, such as Ethernet).

In some embodiments, the power receiving module 320 communicates theamount of power to the communication module 316, which communicates theamount of power to other remote devices (e.g., transmitter 102, FIGS.1-2). Moreover, in some embodiments, the power receiving module 320 maycommunicate the amount of power to database 322 (e.g., the database 322stores the amount of power derived from one or more power waves 116). Insome embodiments, the power receiving module 321 instructs thecommunication module 316 to transmit distinct transmissions to theremote devices (e.g., a first communication signal that indicates afirst amount of power received by the receiver (e.g., by a first testsignal from the transmitter 102), a second communication signal thatindicates a second amount of power received by the receiver (e.g., by asecond test signal from the transmitter 102), and so on if needed).Alternatively, in some embodiments, the power receiving module 320instructs the communication module 316 to transmit data packets to theremote devices (e.g., a respective data packet can include informationfor multiple test signals transmitted by the transmitter 102).

Each of the above identified elements (e.g., modules stored in memory142 of the receiver 120) is optionally stored in one or more of thepreviously mentioned memory devices, and corresponds to a set ofinstructions for performing the function(s) described above. The aboveidentified modules or programs (e.g., sets of instructions) need not beimplemented as separate software programs, procedures, or modules, andthus various subsets of these modules are optionally combined orotherwise rearranged in various embodiments. In some embodiments, thememory 142, optionally, stores a subset of the modules and datastructures identified above. Furthermore, the memory 142, optionally,stores additional modules and data structures not described above, suchas an identifying module for identifying a device type of a connecteddevice (e.g., a device type for an electronic device 122).

On-and-Off Power Detection

FIG. 4A is a schematic of a representative receiver 120 in accordancewith some embodiments. The representative receiver 120 is an example ofthe receiver 120 (FIG. 3). The components in FIG. 4A are illustrated ina particular arrangement for ease of illustration and one skilled in theart will appreciate that other arrangements are possible. Moreover,while some example features are illustrated, various other features havenot been illustrated for the sake of brevity and so as not to obscurepertinent aspects of the example implementations disclosed herein.

In FIG. 4A, the receiver 120 includes an antenna 413 capable ofreceiving wireless power transmission signals (e.g., power waves 116).Once the wireless power transmission signals are received at the antenna413 and converted to an alternating current, the alternating current issent to an input of the coupling mechanism 410. Some examples ofcoupling mechanism 410 are illustrated in FIG. 4C. In some embodiments,the coupling mechanism 410 has two outputs (a first output that suppliesAC alternating current the first rectifier 401, and a second output thatsupplies the alternating current to the second rectifier), and eachoutput receives a portion of the alternating current received at theinput of the coupling mechanism. In some embodiments, the couplingmechanism is configured to send all but −30 dB to −40 dB of thealternating current to the first output of the coupling mechanism 410,and sending the remaining −30 to −40 dB of the alternating current tothe second output of the coupling mechanism 410.

The first output of the coupling mechanism 410 is coupled to an input ofan input matching network 403, which is configured to match theimpedance of the first rectifier with the impedance of the antenna 413.Although one matching network 403 is shown, it is possible to havemultiple input matching networks, as illustrated by numeral 403-n inFIG. 4B. The matching network is designed to match the impedance betweenthe source (e.g., the antenna 413) and the load (e.g., the rectifier401). The output of the matching network(s) is (are) coupled to thefirst rectifier 401. The first rectifier is configured to convert allbut −30 dB to −40 dB of the alternating current to direct current. Someexamples of rectifiers are shown in FIG. 4D. The output of the firstrectifier 401 is coupled in parallel to both a capacitor 404, and thecharging components ZL 406. The capacitor 404, which is also coupled tothe ground, is designed to reduce ripple in the direct current output bythe first rectifier 401, and has a capacitance that matches a directcurrent of the output of the first rectifier. With larger loads (i.e.,rectifier outputs), a larger capacitance may be required, and when thereis a larger capacitance, the capacitor takes a longer time to charge anddischarge (i.e., the voltage to reach a steady state), which slows theresponse time of detecting whether power is no longer being received atthe antenna 413.

The second output of the coupling mechanism is coupled to the secondrectifier 402. The second rectifier 402 converts the remaining −30 dB to−40 dB of the wireless power transmission signals into direct current.Since this −30 dB to −40 dB is roughly less than 1% of the amount ofwireless power transmission signals received at the antenna 413, thecapacitor 405 associated with the second rectifier 402 has a lowercapacitance (relative to the capacitance of the capacitor 404).Consequently, the capacitor 405 in FIG. 4A can charge up and dischargerapidly in comparison to the capacitor 404 coupled to the output of thefirst rectifier 401. As a result, the direct current and/or voltagemeasuring components (“V_(AUX)”) 409-1 detect changes in direct currentpower levels and/or voltage levels in a shorter time span than themeasuring components included in the charging components ZL 406. Themeasuring components (“V_(AUX)”) 409-1 detect the change in wirelesspower transmission signals by either a change in voltage and/or directcurrent, and can then instruct the charging components ZL 406 componentsto prepare for a change in power once the capacitor 404 is eitherdischarging or fully charged.

The second rectifier 402 is also optionally coupled with two resistorsin series (resistor 407 and resistor 408). Between these two resistors,a voltage measurement can also be taken, which acts as anothermeasurement component (“V_(AUX_DIV)”) 409-2. Such an arrangement ofresistors is capable of stepping down the voltage, which allows formeasuring components to have a lower voltage threshold to determinewhether power is increasing or no longer being received. The resistanceof these resistors can be varied depending on the acceptable voltagelevel of the direct current measuring components. In some embodiments,these resistors are variable resistors and are adjusted by a control.Furthermore, resistor 408 is also coupled to the ground.

To help illustrate the benefits of a dual rectifier receiver, graph400-A compares a single rectifier system against a dual rectifiersystem. The graph shows at time “t₁” that the RF power (i.e. thewireless power transmission signals) starts to be received at theantenna 413. “V_(OUT)” shows the output of direct current at the outputof the first rectifier. “V_(AUX)” shows the measuring component 409-1,which shows the output of the second rectifier 402. And, “V_(AUX_DIV)”shows a second measurement point 409-2 that has had its voltage steppeddown by the two resistors, which can be used to activate a measuringcomponent that has a lower voltage threshold.

Moving to time “t₂” the received RF power input remains constant anddoes not change. At time “t₂,” the “V_(OUT)” measuring components arestill seeing a rise in voltage, as opposed to a constant voltage. Onlyonce the voltage has settled can the system utilize the converted directcurrent (DC) (power). While the system is waiting for the voltage tosettle, it is not aware that incoming power is going to the chargingcomponents Z_(L) 406. To counteract this undesirable effect of notpreparing the charging components Z_(L) 406 for the incoming power, asecond rectifier 402 is used in conjunction with a capacitor 405 with asmaller capacitance (relative to capacitor 404) that allows the voltageto settle at time “t₂.” Once the voltage has settled at measuringcomponents 409-1 and 409-2, then the system can communicate with thecharging components Z_(L) 406, (e.g., warn those components thatincoming power is coming despite “V_(OUT)” not yet being settled).

Only at time “t₃” does the first rectifier and capacitor 404 produce asettled voltage that can be used by the system. At time “t₃,” the RFpower is no longer being received at the antenna 413. At time “t₄,” thesmaller capacitance capacitor 405 is able to settle to a voltage levelthat indicates that there is no longer any RF power being received atthe antenna 413 (e.g., 0 volts). Once this lower voltage settles, thecontrol system can notify the charging components Z_(L) 406 that theyshould prepare for powering down. In contrast, at time “t₅” (i.e., longafter time “t₄”), the larger capacitance capacitor 404 fully dischargesand settles to the lower voltage indicating the system is no longerreceiving RF power at the antenna 413. In sum, the charging componentsof the wireless power receiver benefit from an early warning from thesmaller capacitor 405 that power is no longer being received because thecharging components avoid having to wait on the capacitor's 404 longdischarge time before beginning shutdown. Consequently, the earlywarning from the smaller capacitor 405 allows the charging components toprepare for a power down in anticipation of a loss of power, thusprolonging a life of the wireless power receiver (and potentiallycomponents in the device to be charged).

Thus, FIG. 4A at bottom describes a receiver 120 that can apportion asmall amount of its received wireless power for the purpose of improvingreliability of the main components of the circuit (i.e., Z_(L) 406components) by warning these components that a change in power isoccurring. This improved reliability is achieved by anticipating ashutdown, which is discussed in detail in the preceding paragraph.

FIG. 4B is a schematic that illustrates alternative embodiments to thosediscussed with reference to FIG. 4A. Namely, FIG. 4B shows alternativelocations at which the coupling mechanism 410 can be coupled to thecircuit, and still perform the same on-and-off detection as discussed indetail with respect to FIG. 4A. While some example features areillustrated, various other features, which were shown in FIG. 4A, havenot been illustrated in FIG. 4D for the sake of brevity and so as not toobscure pertinent aspects of the example implementations disclosedherein.

The differences between FIG. 4A and FIG. 4B include the addition offirst capacitor 404-a and second capacitor 404-b, and at least a secondmatching network identified as Nth input matching network 403-n.Additionally, four vertical dotted lines represent the differentlocations that the coupling mechanism 410 can be coupled to the circuit.As shown, the coupling mechanism can be coupled to the circuit at apoint before a first capacitor 404-a. Alternatively, the couplingmechanism 410 may also be coupled after the first capacitor 404-a, butbefore the second capacitor 404-b. The next location at which thecoupling mechanism 410 can be coupled to the circuit is the samelocation as the one shown in FIG. 4A. Finally, the coupling mechanism410 can be coupled to the circuit between any of the input matchingnetworks. This is illustrated by the coupling mechanism 410 being placedafter the input matching network 403, but before the coupling mechanism4′0 being placed before the N^(th) input matching network 403-n. In thisexample, the N^(th) input matching network 403-n represents the lastinput matching network.

FIG. 4C is schematic illustrating three separate coupling mechanismembodiments. In some embodiments, the coupling mechanism 410 is adirectional coupler, shown in FIG. 4C as “Coupler A.” The directionalcoupler consists of two separate paths, the first path 458 and thesecond path 459. With reference to both FIG. 4A and FIG. 4B, the firstpath 458 is the path that is coupled to the antenna 413. Path 458 isalso ultimately connected to the first rectifier 401. The second path459 is placed within a certain proximity to the first path 458 so as toallow a portion of the RF signals to bleed off to the second path 459.The second path 459 is ultimately coupled to the second rectifier 402,as shown in FIG. 4A. Additionally, the second path 459 includes aresistor 456 that is coupled to a ground 457.

FIG. 4C also includes schematics for illustrating a capacitive coupler,shown in FIG. 4C as “Coupler B.” The capacitive coupler consists of twoseparate paths, the first path 460 and the second path 461. Withreference to both FIG. 4A and FIG. 4B, the first path 460 is the paththat is coupled to the antenna 413. Path 460 is also ultimatelyconnected to the first rectifier 401. The second path 461 is coupledbetween the first capacitor 462 and second capacitor 463. The secondpath 461 is ultimately coupled to the second rectifier 402, as shown inFIG. 4A. Additionally, the second capacitor 463 is also coupled to aground 464.

FIG. 4C also includes schematics for illustrating a resistive coupler,shown in FIG. 4C as “Coupler C.” The capacitive coupler consists of twoseparate paths, the first path 465 and the second path 466. Withreference to both FIG. 4A and FIG. 4B, the first path 465 is the paththat is coupled to the antenna 413. Path 465 is also ultimatelyconnected to the first rectifier 401. The second path 466 is coupledbetween the first resistor 467 and second resistor 468. The second path466 is ultimately coupled to the second rectifier 402, as shown in FIG.4A. Additionally, the second resistor 486 is also coupled to a ground469.

FIG. 4D shows two schematics for rectifiers. Rectifier “A” illustrates adiode based rectifier. With respect to the diode based rectifier, theinput to the rectifier system is shown as input 448, which is coupled toan anode of a diode 450, and coupled in parallel to the cathode of adiode 451. The cathode of the diode 450 is coupled to the output of therectifier system, as shown as output 449, while the anode of the diode451 is coupled to the ground 452.

FIG. 4D also shows a schematic for a second rectifier, rectifier “B.”Rectifier “B” is a diode connected transistor based rectifier. Withrespect to diode connected transistor based rectifier, the input to therectifier system is shown as input 448, which is coupled, in parallel,to a first diode connected transistor 453, and a second diode connectedtransistor 454. The first diode connected transistor 453 is coupled tothe output of the rectifier system, as shown as output 449, while thesecond diode connected transistor 454 is coupled to the ground 455.

FIG. 4E shows a schematic of a receiver 120 that is similar to thereceiver shown in FIG. 4A. The receiver shown in FIG. 4E, however, doesnot include a coupling mechanism. The purpose of the circuit shown inFIG. 4E is for detecting when the wireless power transmission signalsare no longer being received at the antenna 413, without the use of acoupling mechanism. When the power is no longer detected the receivercan warn components that are coupled to the output of the firstrectifier 401 that the charging components 406 need to prepare forshutdown.

The schematic itself shows an antenna 413 that is coupled to an input ofan input matching network 403. The output of the input matching network403 is coupled to two rectifiers 401, 402 in parallel. Some examples ofmore simplified rectifiers are shown in FIG. 4F. The output of therectifier 401 is coupled in parallel to the both a capacitor 404 andcharging components “Z_(L)” 406. The capacitor 404, which is alsocoupled to the ground 438, is designed to reduce ripple in the DC outputby the first rectifier 401, and has a capacitance that matches the DCload of the output of the first rectifier 401. With larger loads, alarger capacitance is required, and with the larger capacitance, thecapacitor 404 takes a longer time to charge and discharge (i.e., for thevoltage to reach a steady state), which slows the response time ofdetecting whether power is no longer being received at the antenna 413.

The second output of the input matching network 403 is coupled to thesecond rectifier 402. The capacitor 405 in FIG. 4E can charge up anddischarge more rapidly in comparison to the capacitor 404 coupled to theoutput of the first rectifier 401. With respect to the ripple from theoutput of the rectifier 402, the components coupled to the output of therectifier 402 require a less drastic ripple reduction as compared to thecomponents coupled to the output of the rectifier 401. As a result, asmaller capacitance capacitor 405 can be used that allows for fasterdischarge times and, consequently, the DC and/or voltage measuringcomponents (“V_(AUX)”) 409-1 detect changes in DC power levels and/orvoltage levels in a shorter time span than the measuring componentsincluded in the charging components Z_(L) 406. The measuring components(“V_(AUX)”) 409-1 detect the change in wireless power transmissionsignals by a change in voltage and/or DC current, and can then instructthe charging components Z_(L) 406 to prepare for a change in power oncethe capacitor 405 either starts discharging or is fully discharged.

In some embodiments, the second rectifier 402 is also optionally coupledto two resistors in series (resistor 407 and resistor 408, which arecoupled to the ground 437). Between these two resistors a voltagemeasurement can also be taken, which acts as another measurementcomponent (“V_(AUX_DIV)”) 409-2. Such an arrangement of resistors iscapable of stepping down the voltage, which allows for measuringcomponents to have a lower voltage threshold to determine whether poweris no longer being received. The resistance of these resistors can bevaried depending on the acceptable voltage level of the DC measuringcomponents. In some embodiments, these resistors are variable resistorsand are adjusted by a control.

To help illustrate the benefits of a dual rectifier receiver, graph400-B compares a single rectifier system to a dual rectifier system. Thegraph shows at time “t₁” that RF power (i.e. wireless power transmissionsignals) are received at the antenna 413. “V_(OUT)” shows the output ofDC at the output of the first rectifier. “V_(AUX)” shows the measuringcomponent 409-1, which shows the output of the second rectifier 402.And, “V_(AUX_DIV)” shows a second measurement point 409-2 that has hadits voltage stepped down by the two resistors, which can be used toactivate a measuring component that has a lower voltage threshold.

At time “t₂”, the first rectifier 401 and capacitor 404 produce asettled voltage that can be used by the charging components Z_(L) 406.Also at time “t₂”, the RF power is no longer being received at theantenna 413. At time “t₃”, the smaller capacitance capacitor 405 is ableto settle to a voltage level that indicates that there is no longer anyRF power being received at the antenna 413. Once this lower voltagesettles (e.g., at 0 volts), the system can notify the chargingcomponents Z_(L) 406 that they should prepare for powering down. Incontrast, it is not until time “t₄” that the larger capacitor 404 fullydischarges and settles to the lower voltage indicating the system is nolonger receiving RF power at the antenna 413. Warning (i.e., signaling)the charging components that RF power is no longer being received isbeneficial so that those components can prepare for a shutdown inanticipation of a loss of power. Without the second rectifier 402, thecharging components would have to rely solely on the first rectifier 401and the larger capacitor 404 to prepare for shutdown, which as explainedabove is not ideal because the larger capacitor 404 takes a significantamount of time to fully discharge (i.e., an adequate warning cannot begiven to the charging components when the larger capacitance capacitor404 is solely relied upon).

In sum, FIG. 4E ultimately describes a receiver 120 that can apportion asmall amount of its received wireless power for the purpose of improvingreliability of the main components of the circuit (i.e., Z_(L) 406components) by warning these components that the RF power is no longerbeing received at the antenna 413.

Transitioning to FIG. 4F, FIG. 4F illustrates two simplified rectifiersthat are optionally used in rectifiers 401 and 402 in FIG. 4E. Thesesimplified rectifiers are similar to those shown in FIG. 4D, however,since the input of the first rectifier is couple to the input of thesecond rectifier, the second rectifier can be made simpler. AlthoughFIG. 4F shows examples of some rectifiers, any possible diode connectedconfiguration which has reverse bias cut-off characteristics can be usedinstead. With respect to the second rectifier 402, in some embodimentsthe second rectifier 402 is on the same or separate integrated circuitas the first rectifier (i.e., main rectifier) 401. The second rectifier(i.e., auxiliary rectifier) 402, in some embodiments, is a discretesystem on a printed circuit board, package, and/or module.

Power Surge Protection

FIG. 5A is a schematic of a representative receiver 120 in accordancewith some embodiments. The representative receiver 120 is an example ofthe receiver 120 (FIG. 3). The components in FIG. 5A are illustrated ina particular arrangement for ease of illustration and one skilled in theart will appreciate that other arrangements are possible. Moreover,while some example features are illustrated, various other features havenot been illustrated for the sake of brevity and so as not to obscurepertinent aspects of the example implementations disclosed herein.

In FIG. 5A, the receiver 120 includes an antenna 413 capable ofreceiving wireless power transmission signals (also referred to as RFpower). Once the wireless power transmission signals are received at theantenna 413 and converted to an alternating current, the alternatingcurrent is sent to an input of the coupling mechanism 410. Some examplesof coupling mechanism 410 are illustrated in FIG. 4C. In someembodiments, the coupling mechanism 410 has two outputs (a first outputthat supplies the alternating current to the first rectifier, and asecond output that supplies the alternating current to the secondrectifier), and each output receives a portion of the alternatingcurrent received at the input of the coupling mechanism 410. In someembodiments, the coupling mechanism 410 is optionally configured to sendall but −30 dB to −40 dB of the alternating current to the first outputof the coupling mechanism 410, and sending the remaining −30 to −40 dBof the alternating current to the second output of the couplingmechanism 410.

A first output of the coupling mechanism 410 is coupled to an input ofan input matching network 403, which is configured to match theimpedance of the rectifier 401 with the impedance of the antenna 413.Additionally, it is possible to have multiple input matching networks,as illustrated by numeral 403-n. The matching network is designed tomatch the impedance between the source (e.g., the antenna) and the load(e.g., the rectifier). The output of the matching network(s) is coupledto the first (i.e., primary) rectifier 401. The output of the rectifier401 is coupled to a capacitor 503. The capacitor 503, which is alsocoupled to the ground 504, is designed to reduce ripple in the system,and has a capacitance that matches the DC load of the output of thefirst rectifier 401. With larger loads, a larger capacitance is requiredto reduce the ripple, so as to not damage the charging componentsrepresented by numeral 505.

A second output of the coupling mechanism 410 is coupled to the secondrectifier 510 (also referred to as an auxiliary or secondary rectifier).The second rectifier 510 (also referred to as the negative voltagegenerator) converts its received wireless power transmission signalsinto negative voltage. The output of the second rectifier 510 is coupledto a “normally on” active switch 501 that has a gate voltage of 0 voltswhen turned on (i.e., a switch that is in a normally closed state thatcouples the circuit to the ground 502, which causes an impedancemismatch between the rectifier 401 and the antenna 413, which in turncauses the wireless power transmission signals to be reflected by theantenna). The switch 501, when coupled to the ground 502, pulls theoutput of the rectifier 510 to 0 volts. In other words, when the voltagefalls below 0 volts, the switch 501 will gradually begin to open, whichcauses some of the negative voltage to not be directed to the ground502, but instead back to the first output of the coupling mechanism 410.Optionally, as depicted by FIG. 5A, the output of the rectifier 510 canbe coupled either to the first output of the coupling mechanism 410,before or after the input matching network, between two or more matchingnetworks, or before or after the first rectifier 401. When the switch501 allows for some of the current to be directed to the ground 502, animpedance mismatch is created between the antenna and the firstrectifier 401. Once the gate 501 is fully opened and the current withthe negative voltage is no longer being directed to the ground, then thefirst rectifier 401 can match the impedance of the antenna 413, and thewireless power transmission signals will not be reflected by the antenna413.

To illustrate the discussion above, graph 500 shows the gradual openingof the switch 501 stopping the rectifier 401 from receiving a powersurge. As shown in the first top row 500-A of the graph 500, the RFinput power (i.e., the wireless power transmission signals that areconverted to an alternating current) is received at the antenna 413. Thewireless power transmission signals are constant beginning at time “t₁.”The second row 500-B, “Vi_coupled,” illustrates the amount of wirelesspower transmission signals harvested by the antenna 413 (and convertedto the alternating current), and subsequently apportioned by thecoupling mechanism 410. Numeral 506 illustrates the point at which“Vi_coupled” is measured. “Vi_coupled” is constant at time “t₁,” whichcorresponds to the amount of wireless power transmission signals beingreceived at the antenna 413. However, only a portion of the power isreceived at “Vi_coupled” because of the coupling mechanism 410. Even attime “t₂”, the amount of the alternating current measured at“Vi-Coupled” remains constant, due to the coupling mechanism's 410apportionment. In some embodiments, the coupling mechanism 410 candynamically adjust the amount of power that is sent to the negativevoltage rectifier 510.

The third row 500-C of graph 500 illustrates the negative voltagemeasured at point 507 in the circuit illustrated in FIG. 5A. At time“t₁,” which is the same time that the antenna 413 started to receive thealternating current, the rectifier 510 (e.g., a negative voltagegenerator) begins converting the alternating current to a negativevoltage. The negative voltage slowly starts to increase in magnitudeuntil time “t₂,” which at that point the negative voltage has reached anegative voltage threshold.

The fourth row 500-D illustrates the QR switch's (i.e., the switch 501)status. In other words, the fourth row 500-D shows that, depending onthe negative voltage produced by the negative voltage generator 510, theswitch 501 can exist in an on state (“ON”), a partially-on state that isbelow the negative voltage threshold (“Sub_Vth”), and a completely offstate (“OFF”). At any time where the receiver does not receive anywireless power transmission signals, the switch 501 will be in the “ON”state, and will direct incoming current to the ground 502 causing animpedance mismatch at the rectifier 401. This impedance mismatch causesthe wireless power transmission signals to be reflected at the antenna413. At time “t₁”, the alternating current starts to be received at thenegative voltage generator 510, and then the negative voltage generator510 starts producing negative voltage, as discussed above with referenceto the row 500-C. Once the negative voltage starts being produced, theswitch 501 begins to open, which gradually uncouples the circuit at thatpoint from the ground 502. At time “t₂”, the negative voltage thresholdis met, and the switch 501 is completely open and no longer couples theground 502 to the circuit. This consequently reduces the impedancemismatch between the first rectifier 401 and the antenna 413, andresults in less reflection of the wireless power transmission signals.

The fifth row 500-E of graph 500 illustrates the amount of power that iseither reflected or received at the antenna 413 due to the impedancemismatch caused by the switch either being coupled, partially coupled,or uncoupled with the ground 502. Specifically, at time “t₁”, the amountof the wireless power transmission signals reflected is at its highest,meaning that all but the wireless transmission signals apportioned bythe coupling mechanism 410 to be sent to the negative voltage generator510 are reflected at the antenna 413, which is caused by the impedancemismatch between the antenna 413 and the first rectifier 401. As theswitch 501 begins to open between times “t₁” and “t₂”, the impedancemismatch begins to decrease, and as the mismatch begins to decrease, thewireless power transmission signals are reflected at a lesser rate. Whenthe wireless power transmission signals are no longer reflected, theyare directed to the first rectifier 401. After time “t₂”, the voltagethreshold of the switch 501 is met the amount of reflected wirelesstransmission signals is decreased to its lowest state.

The sixth row 500-F of graph 500 illustrates the amount of wirelesspower transmission signals converted to direct current (“V_(RECT)”) bythe first rectifier 401. The measuring point of “V_(RECT)” occurs atpoint 509. At time “t₁”, the rectifier 401 rectifies a portion of thealternating current received at the antenna 413 corresponding to theimpedance mismatch caused the state of the switch 501. Additionally, attime “t₁”, the switch 501 is still primarily coupled to the ground 502,and consequently, the impedance mismatch is still high, meaning that thewireless power transmission signals are reflected by the antenna 413.Since the majority of the wireless power signals are being reflected,the rectifier 401 is not capable of producing a large amount ofrectified power. At time “t₂”, when the switch 501 is no longer coupledto the ground 502, the impedance mismatch between the rectifier 401 andthe antenna 413 is eliminated, thereby allowing the rectifier 401 toreceive the alternating current from the antenna 413.

The seventh row 500-G of graph 500 illustrates measuring point 508 inFIG. 5A. Specifically, row 500-G illustrates what current would bereceived at the input of the rectifier 401 without the negative voltagegenerator 510 and switch 501 (i.e. the surge protector components). Inthe graph 500, the current that is received at the input of therectifier 401 is referred to as “I_(RIN) without surge protection.” Asshown in row 500-G, after time “t₁” a large current spike is shown,which can cause damage to the first rectifier 401, and other relatedcharging components. After the current spike, the current plateaus andno longer has any large variations in magnitude.

The eighth row 500-H of graph 500 illustrates detected current atmeasuring point 508 in FIG. 5A. Specifically, row 500-G shows themeasurement of the current that is received at the input of therectifier 401, when the negative voltage generator 510 and switch 501(i.e. the surge protector components coupled to the circuit) stop surgesin power. This is shown to contrast row 500-G, which shows the currentthat would be flowing to the rectifier 401 if there was no surgeprotection. In the graph, the current with surge protection is referredto as “I_(RIN) with surge protection.” As shown in 500-H, after time“t₁” a gradual increase in current is shown, instead of a large spike asshown in 500-G, that reduces damage to the first rectifier 401 and otherrelated components. After the switch 501 is fully opened the currentplateaus and no longer has any large variations in its magnitude.

FIG. 5B is a schematic that illustrates alternative embodiments to thosepresented in FIG. 5A. Namely, FIG. 5B shows alternative locations atwhich the coupling mechanism 410 can be coupled to the circuit, andstill perform the same surge protection as discussed in detail withrespect to FIG. 5A. While some example features are illustrated, variousother features, which were shown in FIG. 5A, have not been illustratedin FIG. 5B for the sake of brevity and so as not to obscure pertinentaspects of the example implementations disclosed herein.

The differences between FIG. 5A and FIG. 5B include the addition offirst capacitor 404-a and second capacitor 404-b, and at least a secondmatching network identified as N^(th) input matching network 403-n.Additionally, six vertical dotted lines represent the differentlocations that the coupling mechanism 410 can be coupled to the circuit.As shown, the coupling mechanism 410 can be coupled to the circuit at apoint before a first capacitor 404-a. Alternatively, the couplingmechanism 410 may be coupled after the first capacitor 404-a, but beforethe second capacitor 404-b. The next location at which the couplingmechanism 410 can be coupled to the circuit is at the same location asthe one shown in FIG. 5A. The coupling mechanism 410 can be coupled tothe circuit between any of the input matching networks. This isillustrated by the coupling mechanism 410 being placed after the inputmatching network 403, but before the coupling mechanism 410 being placedbefore the N^(th) input matching network 403-n. In this example, theN^(th) input matching network 403-n represents the last input matchingnetwork. The coupling mechanism 410 can also be placed after the lastinput matching network in the series of input matching networks, butbefore the first rectifier 401. Finally, the coupling mechanism 410 mayalso be placed after the rectifier 401, but before the capacitor 404 andZ_(L) 406, which represent the charging components that the receiver iscoupled to.

In-Band Communication

Transitioning to FIG. 6A, FIG. 6A illustrates a way for in-bandcommunication between a wireless power receiver 120 and a wireless powertransmitter 102 without a dedicated communication radio for controllingthe power of the wireless power transmission signals. The components inFIG. 6A are illustrated in a particular arrangement for ease ofillustration and one skilled in the art will appreciate that otherarrangements are possible. Moreover, while some example features areillustrated, various other features have not been illustrated for thesake of brevity and so as not to obscure pertinent aspects of theexample implementations disclosed herein.

FIG. 6A's schematic illustrates one embodiment of a receiver 120.Receiver 120 includes an antenna 413 capable of receiving wireless powertransmission signals. Once the wireless power transmission signals arereceived at the antenna 413 and converted to an alternating current, thewireless power transmission signals are sent to an input of the couplingmechanism 410. Some examples of coupling mechanism 410 are illustratedin FIG. 4C. The coupling mechanism 410 has two outputs (a first outputthat supplies alternating current to the first rectifier 401, and asecond output that supplies alternating current to the second rectifier402), and each output receives a portion of the alternating currentreceived at the input of the coupling mechanism 410. In someembodiments, the coupling mechanism 410 is optionally configured to sendall but −30 dB to −40 dB of the alternating current to the first outputof the coupling mechanism 410, and sending the remaining −30 to −40 dBof the alternating current to the second output of the couplingmechanism 410.

A first output of the coupling mechanism 410 is coupled to an input ofan input matching network 403, which is configured to match theimpedance of the rectifier 402 with the impedance of the antenna 413.Additionally, it is possible to have multiple input matching networks,as illustrated by 403-n in FIG. 6B. The matching network is designed tomatch the impedance between the source (e.g., the antenna 4123) and theload (e.g., the rectifier 401). The output of the matching network(s) is(are) coupled to the first (i.e., primary) rectifier 401. The output ofthe first rectifier 401 is coupled in parallel to the both a capacitor404 and Z_(L) 406, which represent the charging components that thereceiver is coupled to. The capacitor 404, which is also coupled to theground, is designed to reduce ripple of the direct current output by thefirst rectifier 401 in the system, and has a capacitance that matchesthe direct-current load of the output of the first rectifier 401. Withlarger loads (i.e., the rectifier output), a larger capacitance isrequired, and when there is a larger capacitance, the capacitor takes alonger time to charge and discharge (i.e., for voltage to reach a steadystate), which slows the response time of detecting whether power is nolonger or is being received at the antenna 413.

A second output of the coupling mechanism 410 is coupled to anotherinput matching network 414. A second rectifier 402 (also referred to asan auxiliary or secondary rectifier) is coupled to the output of theother (also referred to as the auxiliary input matching network) inputmatching network 414. The second rectifier 402 converts the apportionedalternating current received from the coupling mechanism 410 to directcurrent with a voltage component. The second rectifier 402 is coupled toan adjustable load 601 that can cause a slight impedance mismatch of theother matching network 414. This ultimately causes a portion of wirelesstransmission signals to be reflected by the antenna 413 back to thetransmitter 102. The adjustable load 601 is coupled to a toggle 602, andwhen the toggle 602 is toggled, it causes the adjustable load 601 to betoggled between two different impedances. The purpose of such anadjustable load 601 is to modulate the amount of power reflected by thereceiver 120 in order to communicate with the transmitter 102.

As previously discussed, input matching quality of an RF systemdetermines the amount of power reflected from the antenna 413. In aperfectly matched system there is no reflected power. However, whenthere is an impedance mismatch, some of the wireless power transmissionsignals are reflected from the antenna 413. Reflected wireless powertransmission signals can be detected with a RF signal receivingcircuitry at the transmitter 102. These reflected signals can be used bythe transmitter 102 to determine how much power to send to the receiver120, or when to stop transmitting power to the receiver 120 (e.g., thebattery is sufficiently charged and no longer needs to receive power).To communicate with the transmitter 102, the receiver 120 needs tomodulate the impedance (i.e., so that the reflected signals conveyinformation). This process will be further discussed in relation to thegraph 600 in FIG. 6A.

FIG. 6A's graph 600 demonstrates how the receiver 120 is able tocommunicate with the transmitter 102 by modulating its impedance at theauxiliary matching network. FIG. 6A includes a first row 600-Aillustrating the amount of RF power (also referred to as wireless powertransmission signals) that the antenna 413 is receiving. Between time“t₁” and “t₃”, there is no impedance mismatch, and the full amount ofwireless power transmission signals is received by the antenna 413(e.g., no signals are reflected at the antenna 413). However, at time“t₃” to “t₄”, an impedance mismatch is introduced into the system, whichresults in the amount of RF power received by the antenna 413 todecrease (i.e., some signals are reflected at the antenna 413). As shownat times “t₄” and “t₅”, the toggle 602 (also referred to as “V_(CTR)”),is switched on and off causing the reflection of wireless powertransmission signals to be modulated from no reflection to partialreflection. Various aspects of the “V_(CTR)” such as frequency, dutycycle, pulse width and patterns can be used as a form of signalgeneration (e.g., modulation). This modulation can be used tocommunicate with the transmitter 102 by interpreting certain modulationsas instructions regarding, e.g., how much power the transmitter 102should be sending to the receiver 120. In some embodiments, asillustrated in row 600-A, the modulation received between times “t₄” to“t₅” causes the transmitter 102 to stop transmitting wirelesstransmission signals. As a result, after time “t5” the antenna 413 nolonger receives wireless power transmission signals from the transmitter102. In some embodiments, the transmitter 102 includes a demodulatorthat allows the transmitter 102 to demodulate and process the modulatedsignals generated by the receiver 120. The modulated signals can provideother information in addition to a power requirement for the receiver120. For example, the modulated signals indicate a location of thereceiver 120 relative to the transmitter 102. In another example, themodulated signals may be associated with an authorization key for thereceiver 120 (i.e., once the transmitter 102 receives and processes theauthorization key, the transmitter 102 initiates wireless charging ofthe receiver 120). Various other forms of information may conveyed usingthe modulated signals discussed herein.

In FIG. 6A's graph 600, the second row 600-B shows the voltage thatrectifier 401 is outputting. This measurement point is taken after thecapacitor 404, and is represented by numeral 603 in the circuitschematic in FIG. 6A. Between times “t₁” and “t₂”, the capacitor 404 ischarging up, and only once fully charged does the voltage plateau andremain at a constant magnitude. Between times “t₃” and “t₄”, theimpedance is adjusted. This impedance adjustment, however, is made onlyin relation to the other input matching network 414, which means thatthe alternating current sent to the first rectifier 401 by the couplingmechanism 410 remains the same. Therefore, between times “t₃” and “t₅”,the rectifier 401 is able to output the same amount of rectified powerdespite toggle 602 toggling the impedance of the other input matchingnetwork 414.

In FIG. 6A's graph 600, the third row 600-C shows the toggle 602 (alsoreferred to as the (“V_(CTR)”)) toggling the load impedance of the inputmatching network 414. From times “t₁” to “t₃”, the toggle 602 is in afirst state causing a certain load impedance. In some embodiments, thereis no load impedance between the antenna 413 and the other inputmatching network 414, and none of the wireless power transmissionsignals are reflected by the antenna 413. Between times “t₃” and “t₄”,the toggle 602 is in a second state that causes a certain loadimpedence. The load impedance generated by the toggle 602 being toggledresults in a mismatch with the antenna's 413 impedance, which causes aportion of the wireless power transmission signals to be reflected backto the transmitter 102. This reflected portion of the wireless powertransmission signals is normally not reflected by the antenna 413 (e.g.,when the toggle is in the first state).

In FIG. 6A's graph 600, the fourth row 600-D shows the output voltage bythe second rectifier 402 in response to the toggling of the loadimpedance of the input matching network 414. The point at which theoutput voltage of the second rectifier 402 is demonstrated by numeral604 in FIG. 6A's circuit schematic. Between times “t₁” and “t₃”, thetoggle 602 is in the first state (i.e., no impedance mismatch withantenna 413) while between times “t₃” to “t₄”, the toggle 602 is in thesecond state. Again, when the toggle 602 is in the second state, theimpedance mismatch is greater at the other input matching network 414,and when the impedance mismatch is greater, a greater percentage of thewireless power transmission signals are reflected by the antenna 413.

In FIG. 6A's graph 600, the fifth row 600-E shows the amount of wirelesspower transmission signals that are reflected by antenna 413 when thetoggle 602 is in the second state. In some embodiments, when the toggle602 is in the first state (discussed above), the toggle 602 causes theadjustable load 601 to be adjusted and cause a perfect impedance matchbetween the other input matching network 414 and the antenna 413, whichis illustrated by times “t₁” to “t₃” and portions of “t₄” to “t₅.” Atthese times, an amount of wireless power transmission signals reflectedby the antenna 413 is minimal (if any). At times “t₃” to “t₄” andportions of time “t₄” to “t₅,” however, the toggle 602 is in the secondstate, which causes the adjustable load 601 to be adjusted, whichultimately causes an impedance mismatch between the antenna 413 and theother input matching network 414. When there is an impedance mismatch,at least some of the wireless transmission signals are reflected by theantenna 413, which is shown at times “t₃” to “t₄” and portions of time“t₄” to “t₅.” Although two states of modulation are discussed, it ispossible to modulate the toggles frequency, duty cycle, pulse, width,and patterns.

FIG. 6B is a schematic that illustrates alternative embodiments to thosepresented in FIG. 6A. Namely, FIG. 6B shows alternative locations atwhich the coupling mechanism 410 can be coupled to the circuit and stillperform the same in-band communication techniques discussed in detailwith respect to FIG. 6A. While some example features are illustrated,various other features, which were shown in FIG. 6A, have not beenillustrated in FIG. 6B for the sake of brevity and so as not to obscurepertinent aspects of the example implementations disclosed herein.

The differences between FIG. 6A and FIG. 6B include the addition offirst capacitor 404-a and second capacitor 404-b, and at least a secondmatching network that is coupled to the first rectifier 401, which isidentified as N^(th) input matching network 403-n. Additionally, fivevertical dotted lines represent different locations that the couplingmechanism 410 can be coupled to the circuit. As shown, the couplingmechanism 410 can be coupled to the circuit at a point before a firstcapacitor 404-a. Alternatively, the coupling mechanism 410 may becoupled after the first capacitor 404-a, but before the second capacitor404-b. The next location at which the coupling mechanism 410 can becoupled to the circuit of receiver 120 is at the same location as theone shown in FIG. 6A. The coupling mechanism 410 can be coupled to thecircuit between any of the input matching networks. This is illustratedby the coupling mechanism 410 being placed after the input matchingnetwork 403, but before the coupling mechanism 410 being placed beforethe N^(th) input matching network 403-n. In this example, the N^(th)input matching network 403-n represents the last input matching network.Finally, the coupling mechanism 410 can be placed after the last inputmatching network in the series of input matching networks, but beforethe first rectifier 401.

Finally, FIG. 6C illustrates three separate embodiments for adjustingthe load of the adjustable load 601, two of which are digital adjustableloads, and one of which that is an analog adjustable load. In someembodiments, a single bit digital control can be used. In some otherembodiments, multiple bits can be utilized to increase theresolution/range of the signals that are being generated by the circuit(as shown in in the circuit schematic of FIG. 6A). Although threeembodiments are shown, any equivalent means for adjusting the load canalso be used instead. In some embodiments, the adjustable load is atapped switch with a series of resistors, which is shown in theadjustable load 601-A. Looking at adjustable load 601-A, it includes aninput point 616, which corresponds to the input of the adjustable loadwhere the adjustable load 601-A receives rectified power from the secondrectifier 402, as shown in FIG. 6A's circuit schematic. The input point616 is coupled in parallel to the input of a capacitor 617 and an inputof a resistor 619. The output of the capacitor 617 is coupled to theground 618. The output of the resistor 619 is coupled in parallel to theinput of a resistor 620 and the input to a switch 622. The output of theresistor 620 is coupled to the ground 621. The switch 622 switches whenthe toggle 602 toggles between its two states (e.g., connected to theground, or unconnected from the ground), as discussed in detail in FIG.6A. When the toggle 602 causes the switch 622 to connect to the ground641, the impedance is subsequently changed, which can cause an impedancemismatch between the other input matching network 414 and the antenna413, as shown in FIG. 6A.

In some embodiments, the adjustable load is a series switch withparallel resistors, which is shown in the adjustable load 601-B. Thisadjustable load in this example is a digital adjustable load. In someembodiments, a single bit digital control can be used. In some otherembodiments, multiple bits can be utilized to increase theresolution/range of the signals that are being generated by the circuit(as shown in in the circuit schematic of FIG. 6A). Looking at adjustableload 601-B, it includes an input point 616, which corresponds to theinput of the adjustable load where the adjustable load 601-B receivesrectified power from the second rectifier 402, as shown in FIG. 6A'scircuit schematic. The input point 616 is coupled in parallel with theinput of a capacitor 623, the input of resistor 625, and the input of aresistor 627. The output of the capacitor 623 is coupled to the ground624. The output of the resistor 625 is coupled to the ground 626. Theoutput of the resistor 627 is coupled to a switch 628. The switch 628switches when the toggle 602 toggles between its two states (e.g.,connected to the ground 629, or unconnected from the ground 629), asdiscussed in detail in FIG. 6A. When the toggle 602 causes the switch628 to connect to the ground 629, the impedance is subsequently changed.This causes an impedance mismatch between the other input matchingnetwork 414 and the antenna 413, as shown in FIG. 6A.

In some embodiments, the adjustable load is an analog control and loadthat allows for increased resolution/range of control of the loadimpedance, which is shown in the adjustable load 601-C schematic.Looking at adjustable load 601-C, it includes an input point 616, whichcorresponds to the input of the adjustable load where the adjustableload 601-C receives rectified power from the second rectifier 402, asshown in FIG. 6A's circuit schematic. The input point 616 is coupled inparallel to the input of a capacitor 630, the input of resistor of avariable resistor 632, and the input of a resistor 627. The output ofthe capacitor 623 is coupled to the ground 624. The output of theresistor 625 is coupled to the ground 626. The output of the resistor627 is coupled to a switch 628. The switch 628 switches when the toggle602 toggles between its two states (e.g., connected to the ground, orunconnected from the ground), as discussed in detail in FIG. 6A, and theground 629. When the toggle 602 causes the switch 628 to connect to theground 629, the impedance is subsequently changed, which can cause animpedance mismatch between the other input matching network 414 and theantenna 413, as shown in FIG. 6A.

FIG. 7 shows a method flowchart 700 that describes a process ofcommunication between a wireless power receiver (e.g., receiver 120 inFIG. 6A) and a wireless power transmitter (e.g., transmitter 102). InFIG. 6A, the receiver 120 includes a rectifier 402 (sometimes called asecondary rectifier or an auxiliary rectifier) that is not used todirectly power the main system (e.g., the components that allow thewireless power receiver to use the received energy). One or moreoperations of the method 700 may be performed by the wireless powerreceiver or by one or more components thereof (e.g., those describedabove with reference to FIG. 3). FIG. 7 corresponds to instructionsstored in a computer memory or computer-readable storage medium (e.g.,memory 142 of the receiver 120, FIG. 3).

In some embodiments, the method flowchart 700 includes receiving (702),by an antenna (e.g., antenna 413, FIG. 6A) of the wireless powerreceiver, radio frequency (RF) signals from the wireless powertransmitter. During the receiving (702) (at least initially), thewireless power receiver substantially matches an impedance of thewireless power transmitter.

Moreover, while receiving the RF signals, the method 700 furtherincludes determining (704) whether a communication criterion issatisfied. In some embodiments, the communication criterion is satisfiedwhen an electronic device serviced by the wireless power receiver isfully charged. Alternatively or in addition, in some embodiments, thecommunication criterion is satisfied when there is no obstruction (orless than a predetermined level of obstruction) between the wirelesspower receiver and the wireless power transmitter, and the communicationcriteria is not satisfied when there is an obstruction (or more than apredetermined level of obstruction). In some instances, obstructions mayinclude one or more of humans, pets, or other items that interfere withthe wireless transmission of power, or cause harm to living things.

In some embodiments, in accordance with a determination that thecommunication criterion is not satisfied (704-No), the method 700remains unchanged. In other words, the wireless power receiver continuesto receive the RF signals from the wireless power transmitter.

In some embodiments, in accordance with a determination that thecommunication criterion is satisfied (704-Yes), the method 700 includesintroducing (706) an impedance mismatch between the wireless powerreceiver and the wireless power transmitter that causes a portion of theRF signals to be reflected by the receiver's antenna as a modulatedsignal. In some instances, the wireless power transmitter receives andinterprets the modulated signal without using a separate communicationradio (e.g., a Bluetooth radio is not needed to interpret the modulatedsignal). Rather, the wireless power transmitter is able to receive andinterpret the modulated signal using the same antenna(s) thattransmitted the RF signals in the first place. In some embodiments, theportion can be capped at a certain threshold to stop the receiver fromreflecting too much power back to the transmitter.

In some embodiments, introducing (706) the impedance mismatch includescreating (708) one or more impedance mismatches between the wirelesspower receiver and the wireless power transmitter interspersed with oneor more impedance matches between the wireless power receiver and thewireless power transmitter forming the modulated signal. Interspersingimpedance matches and mismatches to form a modulated signal is discussedin further detail above with reference to FIGS. 6A-6C.

In some embodiments, the wireless power receiver includes an auxiliaryrectifier, coupled to the antenna, that receives some of the RF signals.In such embodiments, introducing (706) the impedance mismatch betweenthe wireless power receiver and the wireless power transmitter includesadjusting a load of the auxiliary rectifier. The auxiliary rectifier maybe a rectifier that is composed of: (i) an input configured to receivethe second portion of the alternating current, (ii) a first diode, and(iii) a second diode, and the input of the secondary rectifier iscoupled to: a cathode of a first diode, wherein an anode of the firstdiode is coupled to a ground; and an anode of a second diode, wherein acathode of the second diode is coupled to an output of the secondaryrectifier. Alternatively, the auxiliary rectifier may be a rectifierthat is composed of: (i) an input configured to receive the secondportion of the alternating current, (ii) a first diode-connectedtransistor, and (iii) a second diode-connected transistor, and the inputof the secondary rectifier is coupled to: (a) a first diode-connectedtransistor, wherein the first diode-connected transistor is connected toa ground, and (b) a second diode-connected transistor, wherein thesecond diode-connected transistor is connected to an output of thesecondary rectifier.

In some embodiments, the wireless power receiver includes an auxiliarymatching network coupled to and positioned between the antenna and theauxiliary rectifier. Furthermore, adjusting the load of the auxiliaryrectifier can cause a mismatch of the auxiliary matching network, whichresults the portion of the RF signals being reflected by the antenna.Moreover, the wireless power receiver may also include a toggle coupledto a load-adjusting mechanism (e.g., a portion of the circuit may beconnected by a switch when then toggle is in one state, and disconnectedwhen the toggle is in another state, which can change the impedance ofthe circuit, see also FIG. 6C illustrating three different types ofmechanisms for adjusting the load), and the load-adjusting mechanism iscoupled to the auxiliary rectifier (e.g., the adjustable loadscomponents shown in FIG. 6C). Furthermore, toggling the switch (e.g.,switch 602 as shown in FIG. 6C) causes a change within theload-adjusting mechanism that produces a change in the load of thereceiver, which results in the impedance mismatch between the wirelesspower receiver and the wireless power transmitter. In some embodiments,adjusting the load of the auxiliary rectifier is done by coupling anoutput of the auxiliary rectifier to a load adjusting mechanism, inparallel, to (i) a capacitor, which is coupled to a ground, and (ii) afirst resistor, where the first resistor is coupled, in parallel, to asecond resistor in series, which is coupled to a ground, and a tappedswitch coupled to the output of the first resistor in series, and aground. The tapped switch is coupled to a toggle for opening and closingthe tapped switch. In some embodiments, the load adjusting mechanismcomprises (i) a capacitor, which is coupled to a ground, (ii) a firstresistor, and (iii) a second resistor, where the second resistor iscoupled to a series switch, which is coupled to a ground. The seriesswitch is coupled to a toggle for opening and closing the series switch.In some embodiments, adjusting the load of the auxiliary rectifier isdone by coupling the output of the auxiliary rectifier, in parallel, to(i) a capacitor, which is coupled to a ground, (ii) a variable resistor,which is coupled to a ground. The variable resistor is coupled to atoggle for adjusting the resistance of the variable resistor.

In some embodiments, in response to the wireless power receiver sendingthe modulated signal, the wireless power transmitter may interpret themodulated signal as an instruction to cease sending the RF signals tothe wireless power receiver. In some other embodiments, in response tothe wireless power receiver sending the modulated signal, the wirelesspower transmitter may interpret the modulated signal as an instructionto adjust transmission characteristics of the RF signals to the wirelesspower receiver (e.g., increase or decrease a power of the RF signals,among other adjustments). In some embodiments, the adjustment is dynamicand depends on the capabilities of the transmitter to handle reflectedsignals.

In some embodiments, after introducing the impedance mismatch and whilecontinuing to receive the RF signals from the wireless powertransmitter, the method further includes matching (710) the impedancebetween the wireless power receiver and the wireless power transmitter,which stops reflection of the portion of the RF signals by the antenna.In some embodiments, the wireless power transmitter ceases to transmitthe RF signals to the wireless power receiver in response to receivingthe modulated signal from the wireless power receiver. In someembodiments, in response to the wireless power receiver sending themodulated signal, the transmitter determines that a threshold amount ofthe reflected signal indicates that the receiver no longer requires RFsignals, and as a result the wireless power transmitter stopstransmitting RF signals to the wireless power receiver. In someembodiments, when a certain percentage is reflected back from thewireless power receiver, but does not exceed a threshold to stop sendingpower, the wireless power transmitter can adjust the amount of RFsignals it is sending to the wireless power receiver.

In light of the principles discussed above, the following embodimentsrelate to converting energy from the received RF signals into analternating current.

In some embodiments, a wireless power receiver is provided thatcomprises: a wireless-power-receiving antenna configured to receiveradio frequency (RF) power signals, and convert energy from the receivedRF signals into an alternating current. In some embodiments, the couplercan be coupled to an output of a first capacitor, and the capacitorsinput is coupled to the antenna. In some embodiments, the coupler can becoupled to the output of a series of capacitors that are coupled to theantenna. In some embodiments, the coupler can be coupled to the outputof the primary rectifier. In some embodiments, the coupler can becoupled after a series of capacitors. In such an embodiment, thecapacitors are used to isolate the coupling point. In some embodiments,the coupler can be coupled to the output of a matching network, or theoutput of a series of matching networks. In some embodiments, a wirelesspower receiver comprises a primary rectifier configured to: (i) receivea first portion of the alternating current, and (ii) rectify the firstportion of the alternating current into primary direct current having afirst voltage and a first power level, the primary direct current usedto provide power or charge to an electronic device. In some embodiments,the primary rectifier is coupled to a capacitor to reduce ripple (e.g.,remove the variations in direct current). In some embodiments the RFcoupler is not used, and the antenna is directly coupled (e.g., a diode)to the primary rectifier and the secondary rectifier. In such anembodiment, an input matching network may be placed between the antennaand the diode. In some embodiments, a wireless power receiver comprisesa secondary rectifier configured to: (i) receive a second portion of thealternating current, and (ii) rectify the second portion of thealternating current into a secondary direct current having a secondvoltage and a second power level. In some embodiments, the directcurrent flows to a capacitor, and then flows to the ground. In someembodiments, the second power level of the secondary direct current isless than the first power level of the primary direct current. In someembodiments, the magnitude of the secondary direct current is a smallamount of the received RF signals, either represented by a decibel valueor a percentage of the incoming RF signals. For example, the power(i.e., voltage, or current) sent to the secondary rectifier can be −30dB to −40 dB, or roughly less than 1% of the RF signals.

In some embodiments, the wireless power receiver's second voltage of thesecondary direct current indicates whether the antenna is receiving RFsignals from a wireless-power-transmitting device. In some embodiments,the magnitude of the secondary direct current can indicate that thesecondary direct current is a minimum current necessary to indicate thatthe antenna is receiving the RF signals from thewireless-power-transmitting device, where the magnitude corresponds to avalue of approximately −30 dB to −40 dB, or roughly 1% of thealternating current, or a voltage level of 1 volt to 40 volts. In someembodiments, the magnitude of the secondary direct current can bemeasured at multiple measurement points (e.g., at V_(AUX) 409-1 andV_(AUX_DIV) 409-2 in FIGS. 4A and 4E), and an amount of voltage detectedat each of the measurement points can be controlled by using one or moreresistors (fixed and/or variable). For example, as shown in FIGS. 4A and4E, a voltage detected at V_(AUX) can be stepped down by using twoin-series resistors, labelled as numerals 407 and 408. These measurementpoints (e.g., at V_(AUX) 409-1 and V_(AUX_DIV) 409-2 in FIGS. 4A and 4E)may be set depending on the type of detection mechanism. A few exampledetection mechanisms are: digital logic detection mechanism, voltagecomparator detection mechanism, and/or an analog to direct currentconverter (ADC) detection mechanism.

When using a digital logic as a detection mechanism, the thresholdvoltage is set to half of the digital logic supply voltage (i.e. whensupply voltage of digital logic is 5 volts, the logic threshold voltagecan be set to be 2.5 volts). When the input is higher than the logicthreshold voltage, the digital logic can output a “low” state thatindicates that the input is lower than the logic threshold voltage. Whenthe input voltage is lower than the logic threshold voltage, the digitallogic can output a “high” state that indicates that the input is higherthan the logic threshold voltage.

When using a voltage comparator as a detection mechanism, the thresholdvoltage can be set to any desired voltage within the supply range byusing a voltage generator (i.e. the threshold voltage can be set to anyvalue within supply voltage of the voltage comparator). When the inputvoltage is higher than the desired threshold voltage, the voltagecomparator can output a “low” state that indicates that the input islower than the desired threshold voltage. When the input voltage islower than the desired threshold voltage, the voltage comparator canoutput a “high” state indicating that the input voltage is higher thandesired threshold voltage.

When using analog to direct current converter (ADC), the threshold canbe set arbitrarily using an external reference voltage. The ADC alsodigitizes the analog voltage value, which is used to tell how far apartthe input voltage is from desired threshold (reference) voltage.

In some embodiments, the wireless power receiver includes an RF couplerthat is coupled to the antenna, the RF coupler comprises distinct firstand second outputs, and the primary rectifier is coupled to the firstoutput of the RF coupler, while the secondary rectifier is coupled tothe second output of the RF coupler.

In some embodiments, the wireless power receiver comprises at least oneimpedance matching network positioned between and coupled to the firstoutput of the RF coupler and the secondary rectifier. In someembodiments, a series of matching networks may be implemented, as shownas 403-n in FIGS. 4B, 5B, and 6B. In some embodiments, the at least onematching network is configured to match an impedance of a source (e.g.,a transmitter) of the RF signals.

In some embodiments, the wireless power receiver comprises at least oneimpedance matching network positioned between and coupled to an input ofthe RF coupler and the antenna, wherein the at least one matchingnetwork is configured to match an impedance of a source of the RFsignals. In some embodiments, the wireless power receiver furthercomprises one or more additional electrical components (e.g., the one ormore additional electrical components are capacitor 404, and Z_(L) 406,which represent the charging components the receiver is coupled to, asshown in FIGS. 4A, 4B, 4E, 6A, and 6B) that are used to deliver theprimary direct current that is used to power or charge to the electronicdevice; and a controller configured to: detect that the second voltageof the secondary direct current satisfies one or more power-detectionthresholds that indicate that the antenna is receiving RF signals from awireless-power-transmitting device; and in response to detecting thatthe second direct current satisfies the one or more power-detectionthresholds, send a signal that causes each of the one or more additionalelectrical components to prepare for receiving the primary directcurrent. In some embodiments the power-detection threshold is met when:(i) the voltage meets a value that corresponds to a received amount ofthe RF power signals (e.g., −40 dB to −1 dB), (ii) the voltage meets avalue that corresponds to a percentage of the RF power signals (e.g.,0.001% to 2%), or (iii) the voltage is within a specified range (e.g., 1volt to 40 volts, 5 volts to 30 volts, 5 volts to 10 volts).

In some embodiments, the one or more power-detection thresholds aresatisfied when the second voltage of the secondary direct current is ina range of approximately 5 volts to 30 volts.

In some embodiments, detecting that the second voltage of the secondarydirect current satisfies one or more power-detection thresholds isperformed by comparing the second voltage to a respectivepower-detection threshold of the one or more power-detection thresholdsat a first measurement point, a second measurement point, or both thefirst and second measurement points.

In some embodiments, the wireless power receiver comprises a firstmeasurement point that is located before a voltage divider that isconfigured to step down the second voltage, and the second measurementpoint is located after the voltage divider. In some embodiments,variable resistors are used to adjust the resistance, and consequentlyadjust the voltage step down.

In some embodiments, the second portion of the alternating current isapproximately 0.01% to 0.1% of the alternating current. And, in otherembodiments, this range can be expanded or retracted, e.g., so that therange is from approximately 0.001% to 10%. In some other embodiments,the second portion of the alternating current range is expanded to coverapproximately less than 1% of the alternating current. In someembodiments, the wireless power receiver comprises: (i) a first storagecomponent (e.g., a first capacitor, or a battery) and (ii) a secondstorage component (e.g., a first capacitor, or a battery) having a lowerstorage capacity than the first storage component (e.g., a firstcapacitor, or a battery); the first storage component (e.g., a firstcapacitor, or a battery) is coupled to an output of the primaryrectifier; the second storage component (e.g., a first capacitor, or abattery) is coupled to an output of the secondary rectifier; the secondstorage component (e.g., a first capacitor, or a battery), due to itslower storage capacity, is configured to discharge faster than the firststorage component (e.g., a first capacitor, or a battery), whereindischarge of the second storage component (e.g., a first capacitor, or abattery) indicates to the wireless power receiver that RF signals are nolonger being received at the antenna, and to prepare components of thewireless power receiver for shutdown.

In some embodiments, the secondary rectifier that is composed of: (i) aninput configured to receive the second portion of the alternatingcurrent, (ii) a first diode, and (iii) a second diode, and the input ofthe secondary rectifier is coupled to: a cathode of a first diode,wherein an anode of the first diode is coupled to a ground; and an anodeof a second diode, wherein a cathode of the second diode is coupled toan output of the secondary rectifier. Although, this embodiment includesthese components, it should be understood that other embodiments includethese components in addition to other components.

In some embodiments, the secondary rectifier is composed of: (i) aninput configured to receive the second portion of the alternatingcurrent, (ii) a first diode-connected transistor, and (iii) a seconddiode-connected transistor, and the input of the secondary rectifier iscoupled to: (i) a first diode-connected transistor, wherein the firstdiode-connected transistor is connected to a ground; and (ii) a seconddiode-connected transistor, wherein the second diode-connectedtransistor is connected to an output of the secondary rectifier.Although, this embodiment includes these components, it should beunderstood that other embodiments include these components in additionto other components.

In some embodiments, the RF coupler is a directional coupler. In someembodiments, a directional coupler is a first path (e.g., a primary RFpath) that is coupled to an antenna configured to receive RF signals andconvert them to alternating current, and a second path (e.g., asecondary RF path) that is not coupled, but placed in parallel with thefirst path. In such an embodiment, the second path can be coupled to aresistor that is coupled to a ground.

In some embodiments, the RF coupler is a capacitive coupler. In someembodiments, a capacitive coupler includes an antenna coupled inparallel with a first capacitor, and a first path (e.g., a primary RFpath). In such an embodiment, the first capacitor is coupled in parallelto a second capacitor, and a second path (e.g., a secondary RF path). Insuch embodiments, the second capacitor can be coupled to a ground.

In some embodiments, the RF coupler is a resistive coupler. In someembodiments, a resistive coupler includes an antenna coupled in parallelwith a first resistor, and a first path (e.g., a primary RF path). Insuch an embodiment, the first resistor is coupled in parallel to asecond resistor, and a second path (e.g., a secondary RF path). In suchembodiments, the second resistor can be coupled to a ground.

In yet another aspect, the discussion below relates to power surgeprotection for a wireless power receiver. A method of power surgeprotection for a wireless power receiver, occurs at a wireless powerreceiver comprising: (i) an antenna, (ii) a rectifier coupled to theantenna, and (iii) a switch coupled to the rectifier, the switchconfigured to create an impedance mismatch or match before an input ofthe rectifier. While the switch is in a default-closed state thatgrounds the switch and creates an impedance mismatch before an input ofthe rectifier: receiving, by the antenna of the wireless power receiver,radio frequency (RF) signals as an alternating current, wherein a firstportion of the alternating current is reflected away from the input ofthe rectifier due to the impedance mismatch, and a second portion of thealternating current flows through the switch and to ground; and whilethe switch is in an open state that creates an impedance match at theinput of the rectifier: the first portion of the alternating currentflows through the input of the rectifier, allowing the first portion ofthe alternating current to be converted into direct current that is usedto charge or power an electronic device; and the second portion of thealternating current flows through the switch and to the input of therectifier, allowing the second portion of the alternating current to beconverted into direct current that is used to charge or power anelectronic device. In this way, a switch can be employed to protect asensitive component (e.g., rectifier) in a wireless-power-receivingcircuit from initial surges of RF energy that may otherwise damage thatsensitive component. In some embodiments, a capacitor may be placedbetween the antenna and the coupling mechanism. In some embodiments, anoutput of the rectifier is coupled to a capacitor that is coupled to aground, which reduces ripple from the conversion of RF signals to directcurrent (DC) signals.

In some embodiments, a negative voltage generator is placed before theswitch. In some embodiments, the negative voltage generator (i.e., arectifier) rectifies RF signals to negative voltage, which causes theswitch to enter an opened state by reaching a zero volt threshold.

In some embodiments, the switch transitions from the default-closedstate to the open state gradually over a period of time, and during theperiod of time, a part of the first portion of the alternating currentcontinues to be reflected away from the input of the rectifier. In someembodiments, over this period of time, the impedance mismatch graduallydecreases, until the mismatch is substantially removed (e.g., less than5% of the mismatch remains). In some embodiments, the period of time isdetermined by the specifications of the switch. In some embodiments, theswitch may be a GaN switch or a depletion mode metal oxide semiconductor(MOS) switch that is designed to open after a set period of time. Insome embodiments, the period of time can be dynamically adjusted basedon a detected voltage of the alternating current.

In some embodiments, dynamically adjusting includes reducing the periodof time based on a determination that the detected voltage does notsatisfy (e.g., less than or equal to) a defined threshold value (e.g.,the defined threshold can be between 4-10 volts, or another appropriatevalue that is slightly above a voltage used to charge a power source ofthe electronic device coupled to the wireless power receiver).

In some embodiments, dynamically adjusting includes increasing theperiod of time based on a determination that the detected voltagesatisfies (e.g., is greater than) a defined threshold value.

In some embodiments, the switch transitions from default-closed to openstate by using a Gallium Nitride (GaN) switch or a depletion mode metaloxide semiconductor (MOS) switch. In some embodiments, the switch has avoltage threshold that is met before it enters the open fully open. Insome embodiments, the voltage threshold is zero volts.

In some embodiments, while the switch is in the open state: ceasing toreceive the RF signals by the antenna of the wireless power receiver.The ceasing to receive the RF signals causes the switch to transitionback to the default-closed state from the open state (e.g., when thevoltage falls below a threshold voltages for the switch, as a result ofno longer receiving the RF signals} {In some embodiments, the switchchanges to the normally closed state when the voltage falls below a zerovolt threshold).

In some embodiments, the wireless power receiver includes a couplingmechanism that is coupled to the antenna, wherein the coupling mechanismincludes a first output and a second output, and further wherein: thefirst output of the coupling mechanism is coupled to the rectifier; andthe second output of the coupling mechanism is coupled to the switch.

In some embodiments, the coupling mechanism partitions the alternatingcurrent, wherein the coupling mechanism: directs a first portion of thealternating current to the first output of the coupling mechanism; anddirects a second portion of the alternating current to the second outputof the coupling mechanism.

In some embodiments, the switch is coupled to an output of therectifier. In some embodiments, the wireless power receiver furthercomprises a matching network having (i) an input coupled to the firstoutput of the coupling mechanism and (ii) an output coupled to therectifier. In some embodiments, more than one matching network may beutilized to match the impedance of the system to the source.

In some embodiments, the switch is coupled to the matching network andthe rectifier. In some embodiments, the switch can be coupled to theoutput of a plurality of matching networks in a series.

Although some of various drawings illustrate a number of logical stagesin a particular order, stages which are not order dependent may bereordered and other stages may be combined or broken out. While somereordering or other groupings are specifically mentioned, others will beobvious to those of ordinary skill in the art, so the ordering andgroupings presented herein are not an exhaustive list of alternatives.Moreover, it should be recognized that the stages could be implementedin hardware, firmware, software, or any combination thereof.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the scope of the claims to the precise forms disclosed. Manymodifications and variations are possible in view of the aboveteachings. The embodiments were chosen in order to best explain theprinciples underlying the claims and their practical applications, tothereby enable others skilled in the art to best use the embodimentswith various modifications as are suited to the particular usescontemplated.

What is claimed is:
 1. A method of power surge protection for a wirelesspower receiver, the method comprising: at a wireless power receivercomprising: (i) an antenna, (ii) a rectifier coupled to the antenna, and(iii) a switch coupled to the rectifier, the switch being configured tocreate an impedance mismatch or match before an input of the rectifier:while the switch is in a default-closed state that grounds the switchand creates an impedance mismatch before an input of the rectifier:receiving, by the antenna of the wireless power receiver, radiofrequency (RF) signals as an alternating current from a wireless powertransmitter, wherein a first portion of the alternating current isreflected away from the input of the rectifier due to the impedancemismatch between the wireless power receiver and the wireless powertransmitter, and a second portion of the alternating current flowsthrough the switch and to ground; and while the switch is in an openstate that creates an impedance match between the wireless powerreceiver and the wireless power transmitter at the input of therectifier: the first portion of the alternating current flows throughthe input of the rectifier, allowing the first portion of thealternating current to be converted into direct current that is used tocharge or power a wireless electronic device; and the second portion ofthe alternating current flows through the switch and to the input of therectifier, allowing the second portion of the alternating current to beconverted into direct current that is used to charge or power a wirelesselectronic device.
 2. The method of claim 1 wherein a negative voltagegenerator is placed to drive the switch.
 3. The method of claim 1,wherein the switch transitions from the default-closed state to the openstate gradually over a period of time, and during the period of time, apart of the first portion of the alternating current continues to bereflected away from the input of the rectifier.
 4. The method of claim3, wherein the switch transitions from the default-closed state to theopen state by using a Gallium Nitride (GaN) switch or a depletion modemetal oxide semiconductor (MOS) switch.
 5. The method of claim 3,further comprising, dynamically adjusting the period of time based on adetected voltage of the alternating current.
 6. The method of claim 5,wherein dynamically adjusting the period of time includes reducing theperiod of time based on a determination that the detected voltage doesnot satisfy a defined threshold value.
 7. The method of claim 5, whereindynamically adjusting the period of time includes increasing the periodof time based on a determination that the detected voltage satisfies adefined threshold value.
 8. The method of claim 1, wherein the switchhas a voltage threshold that is met before it enters a fully open state.9. The method of claim 8, wherein the voltage threshold is zero volts.10. The method of claim 1, further comprising, while the switch is inthe open state: ceasing to receive the RF signals by the antenna of thewireless power receiver, wherein ceasing to receive the RF signalscauses the switch to transition back to the default-closed state fromthe open state.
 11. The method of claim 1, wherein: the wireless powerreceiver includes a coupling mechanism that is coupled to the antenna;the coupling mechanism includes a first output and a second output;: thefirst output of the coupling mechanism is coupled to the rectifier; andthe second output of the coupling mechanism is coupled to the switch.12. The method of claim 11, wherein the coupling mechanism: directs afirst portion of the alternating current to the first output of thecoupling mechanism; and directs a second portion of the alternatingcurrent to the second output of the coupling mechanism.
 13. The methodof claim 11, wherein the switch is coupled to an output of therectifier.
 14. The method of claim 11, wherein the wireless powerreceiver further comprises a matching network having (i) an inputcoupled to the first output of the coupling mechanism and (ii) an outputcoupled to the rectifier.
 15. The method of claim 14, wherein the switchis coupled to the matching network and the rectifier.
 16. A wirelesspower receiver electronic device for power surge protection for awireless power receiver, comprising: an antenna; a rectifier coupled tothe antenna; a switch coupled to the rectifier, the switch beingconfigured to create an impedance mismatch or match before an input ofthe rectifier; one or more processors; and memory storing one or moreprograms for execution by the one or more processors, the one or moreprograms including instructions for: while the switch is in adefault-closed state that grounds the switch and creates an impedancemismatch before an input of the rectifier: receiving, by the antenna ofthe wireless power receiver, radio frequency (RF) signals as analternating current, wherein a first portion of the alternating currentis reflected away from the input of the rectifier due to the impedancemismatch between the wireless power receiver and the wireless powertransmitter, and a second portion of the alternating current flowsthrough the switch and to ground; and while the switch is in an openstate that creates an impedance match between the wireless powerreceiver and the wireless power transmitter at the input of therectifier: the first portion of the alternating current flows throughthe input of the rectifier, allowing the first portion of thealternating current to be converted into direct current that is used tocharge or power a wireless electronic device; and the second portion ofthe alternating current flows through the switch and to the input of therectifier, allowing the second portion of the alternating current to beconverted into direct current that is used to charge or power a wirelesselectronic device.
 17. A non-transitory computer-readable storage mediumstoring one or more programs, the one or more programs comprisinginstructions for communication between a wireless power receiver to awireless power transmitter, that when executed by an electronic devicewith an antenna, a rectifier coupled to the antenna, and a switchcoupled to the rectifier, the switch being configured to create animpedance mismatch or match before an input of the rectifier, one ormore processors and, cause the electronic device to: while the switch isin a default-closed state that grounds the switch and creates animpedance mismatch before an input of the rectifier: receiving, by theantenna of the wireless power receiver, radio frequency (RF) signals asan alternating current, wherein a first portion of the alternatingcurrent is reflected away from the input of the rectifier due to theimpedance mismatch between the wireless power receiver and the wirelesspower transmitter, and a second portion of the alternating current flowsthrough the switch and to ground; and while the switch is in an openstate that creates an impedance match between the wireless powerreceiver and the wireless power transmitter at the input of therectifier: the first portion of the alternating current flows throughthe input of the rectifier, allowing the first portion of thealternating current to be converted into direct current that is used tocharge or power a wireless electronic device; and the second portion ofthe alternating current flows through the switch and to the input of therectifier, allowing the second portion of the alternating current to beconverted into direct current that is used to charge or power a wirelesselectronic device.